Merge branch 'tools' into tools_merge
commit
d76be2f428
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@ -12,7 +12,7 @@ You can download data from [here](http://rebel13.nl/index.html)
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## Convert pgn files
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**Important : convert text will be superheavy (approx 200 byte / position)**
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**Important : convert text will be superheavy (approx 200 byte / position)**
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python pgn_to_plain.py --pgn "pgn/*.pgn" --start_ply 1 --output converted_pgn.txt
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@ -61,7 +61,7 @@ def parse_comment_for_score(comment_str: str, board: chess.Board) -> int:
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score = 0
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return score
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def parse_game(game: chess.pgn.Game, writer, start_play: int=1)->None:
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board: chess.Board = game.board()
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if not game_sanity_check(game):
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@ -105,6 +105,6 @@ def main():
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break
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parse_game(game, f, args.start_ply)
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f.close()
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if __name__=="__main__":
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main()
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15
src/misc.h
15
src/misc.h
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@ -27,6 +27,7 @@
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#include <ostream>
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#include <string>
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#include <vector>
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#include <iostream>
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#include <cstdint>
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#include <cmath>
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@ -52,6 +53,20 @@ void dbg_hit_on(bool c, bool b);
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void dbg_mean_of(int v);
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void dbg_print();
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/// Debug macro to write to std::err if NDEBUG flag is set, and do nothing otherwise
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#if defined(NDEBUG)
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#define debug 1 && std::cerr
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#else
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#define debug 0 && std::cerr
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#endif
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inline void hit_any_key() {
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#ifndef NDEBUG
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debug << "Hit any key to continue..." << std::endl << std::flush;
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system("read"); // on Windows, should be system("pause");
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#endif
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}
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typedef std::chrono::milliseconds::rep TimePoint; // A value in milliseconds
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static_assert(sizeof(TimePoint) == sizeof(int64_t), "TimePoint should be 64 bits");
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inline TimePoint now() {
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944
src/search.cpp
944
src/search.cpp
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@ -47,6 +47,7 @@ namespace Search {
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using std::string;
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using Eval::evaluate;
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using namespace Search;
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using namespace std;
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bool Search::prune_at_shallow_depth = true;
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@ -1965,7 +1966,10 @@ namespace Search
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// Zero initialization of the number of search nodes
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th->nodes = 0;
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// Clear all history types. This initialization takes a little time, and the accuracy of the search is rather low, so the good and bad are not well understood.
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// Clear all history types. This initialization takes a little time, and
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// the accuracy of the search is rather low, so the good and bad are
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// not well understood.
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// th->clear();
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// Evaluation score is from the white point of view
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@ -2183,6 +2187,944 @@ namespace Search
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return ValueAndPV(bestValue, pvs);
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}
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// This implementation of the MCTS is heavily based on Stephane Nicolet's work here
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// https://github.com/snicolet/Stockfish/commit/28501872a1e7ce84dd1f38ab9e59c5adb0d24b41
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// and the adjusted implementation of it in ShashChess https://github.com/amchess/ShashChess
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namespace MCTS
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{
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static constexpr float sigmoidScale = 600.0f;
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static inline float fast_sigmoid(float x) {
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bool negative = x < 0.0f;
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if (negative)
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x = -x;
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const float xx = x*x;
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const float v = 1.0f / (1.0f + 1.0f / (1.0f + x + xx*(0.555f + xx*0.143f)));
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if (negative)
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return 1.0f - v;
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else
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return v;
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}
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static inline Value reward_to_value(float r) {
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if (r > 0.99f) return VALUE_KNOWN_WIN;
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if (r < 0.01f) return -VALUE_KNOWN_WIN;
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return Value(-sigmoidScale * std::log(1.0f/r - 1.0f));
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}
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static inline float value_to_reward(Value v) {
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return fast_sigmoid(static_cast<float>(v) * (1.0f / sigmoidScale));
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}
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// struct MCTSNode : store info at one node of the MCTS algorithm
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struct MCTSNode {
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Key posKey = 0; // for consistency checks
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MCTSNode* parent = nullptr; // only nullptr for the root node
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unique_ptr<MCTSNode[]> children = nullptr; // only nullptr for nodes that have not been expanded
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uint64_t numVisits = 0; // the number of playouts for this node and all descendants
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Value leafSearchEval = VALUE_NONE; // the evaluation from AB playout
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float prior = 0.0f; // the policy, currently a rough estimation based on the playout of the parent
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float actionValue = 0.0f; // the accumulated rewards
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float actionValueWeight = 0.0f; // the maximum value for the accumulater rewards
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Move prevMove = MOVE_NONE; // the move on the edge from the parent
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int numChildren = 0; // the number of legal moves, filled on expansion
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int childId = 0; // the index of this node in the parent's children array
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Depth leafSearchDepth = DEPTH_NONE; // the depth with which the AB playout was done
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bool isTerminal = false; // whether the node is terminal. Terminal nodes are always "expanded" immediately.
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// ucb_value() calculates the upper confidence bound of a child.
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// When searching for the node to expand/playout we take one with the highest ucb.
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float ucb_value(MCTSNode& child, float explorationFactor, bool flipPerspective = false) const
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{
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assert(explorationFactor >= 0.0f);
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assert(child.actionValue >= 0.0f);
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assert(child.actionValueWeight >= 0.0f);
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assert(child.actionValue <= child.actionValueWeight);
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assert(child.prior >= 0.0f);
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assert(child.prior <= 1.0f);
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// For the nodes which have not been played-out we use the prior.
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// Otherwise we have some averaged score or the eval already.
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float reward = child.numVisits == 0 ? child.prior
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: child.actionValue / child.actionValueWeight;
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if (flipPerspective)
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reward = 1.0f - reward;
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// The exploration factor.
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// In theory unplayed nodes should have priority, but we
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// add 1 to avoid div by 0 so they might not always be prioritized.
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if (explorationFactor != 0.0f)
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reward +=
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explorationFactor
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* std::sqrt(std::log(1.0 + numVisits) / (1.0 + child.numVisits));
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assert(!std::isnan(reward));
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assert(reward >= 0.0f);
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return reward;
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}
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// get_best_child() returns a const reference to the best child node,
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// according to the UCB value.
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const MCTSNode& get_best_child(float explorationFactor) const
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{
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assert(!is_leaf());
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assert(numChildren > 0);
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if (numChildren == 1)
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{
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assert(children[0].childId == 0);
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return children[0];
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}
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int bestIdx = -1;
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float bestValue = std::numeric_limits<float>::lowest();
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for (int i = 0 ; i < numChildren ; ++i)
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{
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MCTSNode& child = children[i];
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// The "best" is the one with the best UCB.
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// Child values are with opposite signs.
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const float r = ucb_value(child, explorationFactor, true);
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if (r > bestValue)
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{
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bestIdx = i;
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bestValue = r;
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}
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}
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assert(bestIdx >= 0);
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assert(bestIdx < numChildren);
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assert(children[bestIdx].childId == bestIdx);
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return children[bestIdx];
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}
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// get_best_child() : like the previous one, but does not return a const reference
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MCTSNode& get_best_child(float explorationFactor) {
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return const_cast<MCTSNode&>(static_cast<const MCTSNode*>(this)->get_best_child(explorationFactor));
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}
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// get_best_move() returns a pair (move,value) leading to the best child,
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// according to the action value heuristic.
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std::pair<Move, Value> get_best_move() const {
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assert(!is_leaf());
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assert(numChildren > 0);
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int bestIdx = -1;
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float bestValue = std::numeric_limits<float>::lowest();
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for (int i = 0; i < numChildren ; ++i)
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{
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MCTSNode& child = children[i];
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// The "best" is the one with the best action value.
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// Child values are with opposite signs.
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const float r = 1.0f - (child.actionValue / child.actionValueWeight);
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if (r > bestValue)
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{
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bestIdx = i;
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bestValue = r;
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}
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}
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assert(bestIdx >= 0);
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assert(bestIdx < numChildren);
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assert(children[bestIdx].childId == bestIdx);
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return { children[bestIdx].prevMove, reward_to_value(bestValue) };
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}
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// get_child_by_move() finds a child, given the move that leads to it
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const MCTSNode* get_child_by_move(Move move) const {
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for (int i = 0; i < numChildren ; ++i)
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{
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MCTSNode& child = children[i];
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if (child.prevMove == move)
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return &child;
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}
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return nullptr;
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}
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// get_child_by_move() : like the previous one, but does not return a const
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MCTSNode* get_child_by_move(Move move) {
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return const_cast<MCTSNode*>(static_cast<const MCTSNode*>(this)->get_child_by_move(move));
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}
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// is_root() returns true when node is the root
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bool is_root() const {
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return parent == nullptr;
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}
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// is_leaf() returns true when node is a leaf
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bool is_leaf() const {
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return children == nullptr;
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}
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};
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// struct BackpropValues is a structure to manipulate the kind of stuff
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// that needs to be back-propagated down and up the tree by MCTS.
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struct BackpropValues {
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|
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uint64_t numVisits = 0;
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float actionValue = 0.0f;
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float actionValueWeight = 0.0f;
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|
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// We always keep everything for the side to move perspective.
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// When changing the side the score flips.
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void flip_side() {
|
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assert(actionValueWeight >= actionValue);
|
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assert(actionValue >= 0.0f);
|
||||
assert(actionValueWeight >= 0.0f);
|
||||
|
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actionValue = actionValueWeight - actionValue;
|
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}
|
||||
};
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||||
|
||||
|
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// struct MonteCarloTreeSearch implements the methods for the MCTS algorithm
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|
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struct MonteCarloTreeSearch {
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|
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// IMPORTANT:
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||||
// The position is stateful so we always have one.
|
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// It has to match certain expectations in different functions.
|
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// For example when looking for the node to expand the pos must correspond
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// to the root mcts node. When expanding the node it must correspond to the
|
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// node being expanded, etc.
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static constexpr Depth terminalEvalDepth = Depth(255);
|
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|
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// We add a lot of stuff to the actionValue, but the weights differ.
|
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// The prior is currently bad so low weight,
|
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static constexpr float priorWeight = 0.01f;
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static constexpr float terminalWeight = 1.0f; // could be increased? Different for wins/draws?
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static constexpr float normalWeight = 1.0f;
|
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|
||||
static_assert(priorWeight > 0.0f);
|
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static_assert(terminalWeight > 0.0f);
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static_assert(normalWeight > 0.0f);
|
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|
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MonteCarloTreeSearch() {}
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MonteCarloTreeSearch(const MonteCarloTreeSearch&) = delete;
|
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|
||||
|
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// search_new() : let's start the search !
|
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|
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ValueAndPV search_new(
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Position& pos,
|
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std::uint64_t maxPlayouts,
|
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Depth leafDepth,
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float explorationFactor = 0.25f) {
|
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|
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init_for_mcts_search(pos);
|
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return search_continue(pos, maxPlayouts, leafDepth, explorationFactor);
|
||||
}
|
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|
||||
|
||||
// search_continue_after_move() : continue after a move and reuse the relevant
|
||||
// part of the tree. The prevMove is the move that lead to position 'pos'.
|
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//
|
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// TODO: make the node limit be the total.
|
||||
|
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ValueAndPV search_continue_after_move( Position& pos,
|
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Move prevMove,
|
||||
std::uint64_t maxPlayouts,
|
||||
Depth leafDepth,
|
||||
float explorationFactor = 0.25f) {
|
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do_move_at_root(pos, prevMove);
|
||||
return search_continue(pos, maxPlayouts, leafDepth, explorationFactor);
|
||||
}
|
||||
|
||||
|
||||
// get_all_continuations() is missing description
|
||||
|
||||
std::vector<MctsContinuation> get_all_continuations() const {
|
||||
|
||||
std::vector<MctsContinuation> continuations;
|
||||
continuations.resize(rootNode.numChildren);
|
||||
|
||||
for (int i = 0; i < rootNode.numChildren; ++i)
|
||||
{
|
||||
MCTSNode& child = rootNode.children[i];
|
||||
|
||||
auto& cont = continuations[i];
|
||||
|
||||
cont.numVisits = child.numVisits;
|
||||
cont.value = reward_to_value(cont.actionValue);
|
||||
cont.pv = get_pv(child);
|
||||
cont.actionValue = 1.0f - (child.actionValue / child.actionValueWeight); // child value is with opposite sign
|
||||
}
|
||||
|
||||
std::stable_sort( continuations.begin(),
|
||||
continuations.end(),
|
||||
[](const auto& lhs, const auto& rhs) { return lhs.value > rhs.value; }
|
||||
);
|
||||
|
||||
return continuations;
|
||||
}
|
||||
|
||||
|
||||
// search_continue() : continues with the same tree
|
||||
|
||||
ValueAndPV search_continue( Position& pos,
|
||||
std::uint64_t maxPlayouts,
|
||||
Depth leafDepth,
|
||||
float explorationFactor = 0.25f) {
|
||||
|
||||
if (rootNode.leafSearchDepth == DEPTH_NONE)
|
||||
do_playout(pos, rootNode, leafDepth);
|
||||
|
||||
while (numPlayouts < maxPlayouts)
|
||||
{
|
||||
debug << "Starting iteration " << numPlayouts << endl;
|
||||
do_search_iteration(pos, leafDepth, explorationFactor);
|
||||
}
|
||||
|
||||
if (rootNode.is_leaf())
|
||||
return {};
|
||||
else
|
||||
return { rootNode.get_best_move().second, get_pv() };
|
||||
}
|
||||
|
||||
|
||||
Stack stackBuffer [MAX_PLY + 10];
|
||||
StateInfo statesBuffer[MAX_PLY + 10];
|
||||
|
||||
Stack* stack = stackBuffer + 7;
|
||||
StateInfo* states = statesBuffer + 7;
|
||||
|
||||
MCTSNode rootNode;
|
||||
|
||||
int ply = 1;
|
||||
int maximumPly = ply; // Effectively the selective depth.
|
||||
std::uint64_t numPlayouts = 0;
|
||||
|
||||
private :
|
||||
|
||||
// reset_stats(), recalculate_stats() and accumulate_stats_recursively()
|
||||
// are used to recalculate the number of playouts in our MCTS tree. Note
|
||||
// that at the moment we call recalculate_stats() each time we play a move
|
||||
// at root, to recalculate the stats in the subtree.
|
||||
|
||||
void reset_stats() {
|
||||
numPlayouts = 0;
|
||||
}
|
||||
|
||||
void accumulate_stats_recursively(MCTSNode& node) {
|
||||
|
||||
if (node.leafSearchDepth != DEPTH_NONE)
|
||||
numPlayouts += 1;
|
||||
|
||||
if (!node.is_leaf())
|
||||
for (int i = 0; i < node.numChildren; ++i)
|
||||
accumulate_stats_recursively(node.children[i]);
|
||||
}
|
||||
|
||||
void recalculate_stats() {
|
||||
reset_stats();
|
||||
accumulate_stats_recursively(rootNode);
|
||||
}
|
||||
|
||||
|
||||
// do_move_at_root() is missing description
|
||||
// Tree reuse (?)
|
||||
// pos is the position after move.
|
||||
|
||||
void do_move_at_root(Position& pos, Move move) {
|
||||
|
||||
MCTSNode* child = rootNode.get_child_by_move(move);
|
||||
if (child == nullptr)
|
||||
create_new_root(pos);
|
||||
else
|
||||
{
|
||||
rootNode = std::move(*child);
|
||||
rootNode.parent = nullptr;
|
||||
rootNode.childId = 0;
|
||||
// keep rootNode.prevMove for move ordering heuristics
|
||||
}
|
||||
|
||||
recalculate_stats();
|
||||
|
||||
assert(rootNode.posKey == pos.key());
|
||||
}
|
||||
|
||||
|
||||
// do_search_iteration() does one iteration of the search.
|
||||
//
|
||||
// Basically:
|
||||
// 1. find a node to expand/playout
|
||||
// 2. if the node is a terminal then we just get the stuff and backprop
|
||||
// 3. if we only have prior for the node then do a playout
|
||||
// 4. otherwise we expand the children and do at least one playout from the best child (chosen by prior)
|
||||
// 4.1. a terminal node counts as a playout. All terminal nodes are played out.
|
||||
// 5. Backpropagate all changes down the tree.
|
||||
|
||||
void do_search_iteration(Position& pos, Depth leafDepth, float explorationFactor) {
|
||||
|
||||
MCTSNode& node = find_node_to_expand_or_playout(pos, explorationFactor);
|
||||
BackpropValues backprops{};
|
||||
if (node.isTerminal)
|
||||
{
|
||||
debug << "Root is terminal" << endl;
|
||||
backprops.numVisits = 1;
|
||||
backprops.actionValue += node.actionValue;
|
||||
backprops.actionValueWeight += node.actionValueWeight;
|
||||
|
||||
numPlayouts += 1;
|
||||
}
|
||||
else if (node.leafSearchDepth == DEPTH_NONE)
|
||||
{
|
||||
// The node is considered the best but it only has a prior value.
|
||||
// We don't really want to expand nodes based just on the prior, so
|
||||
// first do a playout to get a better estimate, and expand only in the
|
||||
// next iteration.
|
||||
// Normally we playout immediately the move with the best prior, but that
|
||||
// playout can put it below another move.
|
||||
backprops = do_playout(pos, node, leafDepth);
|
||||
}
|
||||
else
|
||||
{
|
||||
// We have done leaf evaluation with AB search so we know that
|
||||
// this node is *actually good* and not just *prior good*, so we
|
||||
// can now expand it and do an immediate playout for the node with the best prior.
|
||||
backprops = expand_node_and_do_playout(pos, node, leafDepth, explorationFactor);
|
||||
}
|
||||
|
||||
backpropagate(pos, node, backprops);
|
||||
}
|
||||
|
||||
|
||||
// Backpropagates() is the function we use to back-propagate the changes
|
||||
// after an expand/playout, all the way to the root. The position 'pos'
|
||||
// is expected to be at the node from which we start backpropagating.
|
||||
|
||||
void backpropagate(Position& pos, MCTSNode& node, BackpropValues backprops) {
|
||||
|
||||
assert(node.posKey == pos.key());
|
||||
assert(ply >= 1);
|
||||
|
||||
debug << "Backpropagating: " << pos.fen() << endl;
|
||||
|
||||
MCTSNode* currentNode = &node;
|
||||
while (!currentNode->is_root())
|
||||
{
|
||||
// On each descent we switch the side to move
|
||||
|
||||
undo_move(pos);
|
||||
currentNode = currentNode->parent;
|
||||
backprops.flip_side();
|
||||
|
||||
debug << "Backprop step: " << pos.fen() << endl;
|
||||
assert(currentNode->posKey == pos.key());
|
||||
|
||||
currentNode->numVisits += backprops.numVisits;
|
||||
currentNode->actionValue += backprops.actionValue;
|
||||
currentNode->actionValueWeight += backprops.actionValueWeight;
|
||||
}
|
||||
|
||||
// At the end we must be at the root
|
||||
|
||||
assert(currentNode == &rootNode);
|
||||
assert(rootNode.posKey == pos.key());
|
||||
}
|
||||
|
||||
|
||||
// find_node_to_expand_or_playout() navigates from pos to the node to expand/playout,
|
||||
// according to the get_best_child() heuristics.
|
||||
|
||||
MCTSNode& find_node_to_expand_or_playout(Position& pos, float explorationFactor) {
|
||||
assert(rootNode.posKey == pos.key());
|
||||
|
||||
// Find a node that has not yet been expanded
|
||||
MCTSNode* currentNode = &rootNode;
|
||||
while (!currentNode->is_leaf())
|
||||
{
|
||||
MCTSNode& bestChild = currentNode->get_best_child(explorationFactor);
|
||||
|
||||
do_move(pos, *currentNode, bestChild);
|
||||
|
||||
currentNode = &bestChild;
|
||||
}
|
||||
|
||||
return *currentNode;
|
||||
}
|
||||
|
||||
|
||||
// generate_moves_unordered() generates moves in a random order
|
||||
|
||||
int generate_moves_unordered(Position& pos, Move* out) const {
|
||||
int moveCount = 0;
|
||||
for (auto move : MoveList<LEGAL>(pos))
|
||||
out[moveCount++] = move;
|
||||
|
||||
return moveCount;
|
||||
}
|
||||
|
||||
|
||||
// generate_moves_ordered() generates moves with some reasonable ordering.
|
||||
// Using this function, we can assume some reasonable priors.
|
||||
|
||||
int generate_moves_ordered(Position& pos, MCTSNode& node, Depth leafDepth, Move* out) const {
|
||||
assert(ply >= 1);
|
||||
|
||||
debug << "Generating moves: " << pos.fen() << endl;
|
||||
|
||||
Thread* const thread = pos.this_thread();
|
||||
const Square prevSq = to_sq(node.prevMove);
|
||||
const Move countermove = thread->counterMoves[pos.piece_on(prevSq)][prevSq];
|
||||
const Move ttMove = MOVE_NONE; // TODO: retrieve tt move
|
||||
const Move* const killers = stack[ply].killers;
|
||||
const Depth depth = leafDepth + 1;
|
||||
|
||||
const PieceToHistory* contHist[] = {
|
||||
stack[ply-1].continuationHistory, stack[ply-2].continuationHistory,
|
||||
nullptr , stack[ply-4].continuationHistory,
|
||||
nullptr , stack[ply-6].continuationHistory
|
||||
};
|
||||
|
||||
assert(contHist[0] != nullptr);
|
||||
assert(contHist[1] != nullptr);
|
||||
assert(contHist[3] != nullptr);
|
||||
assert(contHist[5] != nullptr);
|
||||
|
||||
MovePicker mp(
|
||||
pos,
|
||||
ttMove,
|
||||
depth,
|
||||
&(thread->mainHistory),
|
||||
&(thread->lowPlyHistory),
|
||||
&(thread->captureHistory),
|
||||
contHist,
|
||||
countermove,
|
||||
killers,
|
||||
ply
|
||||
);
|
||||
|
||||
int moveCount = 0;
|
||||
while (true)
|
||||
{
|
||||
const Move move = mp.next_move();
|
||||
debug << "Generated move " << UCI::move(move, false) << ": " << pos.fen() << endl;
|
||||
|
||||
if (move == MOVE_NONE)
|
||||
break;
|
||||
|
||||
if (pos.legal(move))
|
||||
out[moveCount++] = move;
|
||||
}
|
||||
|
||||
debug << "Generated " << moveCount << " legal moves: " << pos.fen() << endl;
|
||||
|
||||
return moveCount;
|
||||
}
|
||||
|
||||
|
||||
// init_for_leaf_search() prepares some global variables in the thread of the
|
||||
// given position, for compatibility with the normal AB search of Stockfish.
|
||||
// This allows us to use that AB search to get an estimated value of the leaf,
|
||||
// if necessary.
|
||||
|
||||
void init_for_leaf_search(Position& pos) {
|
||||
|
||||
auto th = pos.this_thread();
|
||||
|
||||
th->completedDepth = 0;
|
||||
th->selDepth = 0;
|
||||
th->rootDepth = 0;
|
||||
th->nmpMinPly = th->bestMoveChanges = th->failedHighCnt = 0;
|
||||
th->ttHitAverage = TtHitAverageWindow * TtHitAverageResolution / 2;
|
||||
th->nodes = 0;
|
||||
}
|
||||
|
||||
|
||||
// terminal_value() checks whether the position is terminal. We return
|
||||
// the right value if position is terminal, otherwise we return VALUE_NONE.
|
||||
|
||||
Value terminal_value(Position& pos) const {
|
||||
|
||||
if (MoveList<LEGAL>(pos).size() == 0)
|
||||
return pos.checkers() ? VALUE_MATE : -VALUE_MATE;;
|
||||
|
||||
if (ply >= MAX_PLY - 2 || pos.is_draw(ply - 1))
|
||||
return VALUE_DRAW;
|
||||
|
||||
return VALUE_NONE;
|
||||
}
|
||||
|
||||
|
||||
// evaluate_leaf() does AB search on the position to get its value
|
||||
|
||||
Value evaluate_leaf(Position& pos, MCTSNode& node, Depth leafDepth) {
|
||||
|
||||
assert(node.posKey == pos.key());
|
||||
assert(node.leafSearchDepth == DEPTH_NONE);
|
||||
assert(node.leafSearchEval == VALUE_NONE);
|
||||
|
||||
debug << "Evaluating leaf: " << pos.fen() << endl;
|
||||
|
||||
init_for_leaf_search(pos);
|
||||
|
||||
Move pv[MAX_PLY + 1];
|
||||
stack[ply].pv = pv;
|
||||
stack[ply].currentMove = MOVE_NONE;
|
||||
stack[ply].excludedMove = MOVE_NONE;
|
||||
|
||||
if (!node.is_root() && node.parent->leafSearchEval != VALUE_NONE)
|
||||
{
|
||||
// If we have some parent score then use an aspiration window.
|
||||
// We know what to expect.
|
||||
Value delta = Value(18);
|
||||
Value alpha = std::max(node.parent->leafSearchEval - delta, -VALUE_INFINITE);
|
||||
Value beta = std::min(node.parent->leafSearchEval + delta, VALUE_INFINITE);
|
||||
while (true)
|
||||
{
|
||||
const Value value = Stockfish::search<PV>(pos, stack + ply, alpha, beta, leafDepth, false);
|
||||
if (value <= alpha)
|
||||
{
|
||||
beta = (alpha + beta) / 2;
|
||||
alpha = std::max(value - delta, -VALUE_INFINITE);
|
||||
}
|
||||
else
|
||||
if (value >= beta)
|
||||
beta = std::min(value + delta, VALUE_INFINITE);
|
||||
else
|
||||
return value;
|
||||
|
||||
delta += delta / 4 + 5;
|
||||
}
|
||||
}
|
||||
|
||||
else
|
||||
// If no parent score then do infinite aspiration window.
|
||||
return Stockfish::search<PV>(pos, stack + ply, -VALUE_INFINITE, VALUE_INFINITE, leafDepth, false);
|
||||
}
|
||||
|
||||
|
||||
// get_pv(node) tries to get a pv, starting from the given node
|
||||
|
||||
std::vector<Move> get_pv(const MCTSNode& node) const {
|
||||
std::vector<Move> pv;
|
||||
|
||||
const MCTSNode* currentNode = &node;
|
||||
if (!currentNode->is_root())
|
||||
pv.emplace_back(currentNode->prevMove);
|
||||
|
||||
while (!currentNode->is_leaf())
|
||||
{
|
||||
// No exploration factor for choosing the PV.
|
||||
const MCTSNode& bestChild = currentNode->get_best_child(0.0f);
|
||||
pv.emplace_back(bestChild.prevMove);
|
||||
currentNode = &bestChild;
|
||||
}
|
||||
|
||||
return pv;
|
||||
}
|
||||
|
||||
|
||||
// get_pv() tries to get the pv, starting from the root
|
||||
|
||||
std::vector<Move> get_pv() const {
|
||||
return get_pv(rootNode);
|
||||
}
|
||||
|
||||
|
||||
// do_playout() does a single playout and returns what is needed to backprop
|
||||
|
||||
BackpropValues do_playout(Position& pos, MCTSNode& node, Depth leafDepth) {
|
||||
|
||||
assert(node.posKey == pos.key());
|
||||
assert(node.numVisits == 0);
|
||||
assert(node.is_leaf());
|
||||
assert(node.numChildren == 0);
|
||||
assert(node.leafSearchDepth == DEPTH_NONE);
|
||||
assert(!node.isTerminal);
|
||||
|
||||
debug << "Doing playout " << numPlayouts << ": " << pos.fen() << endl;
|
||||
|
||||
numPlayouts += 1;
|
||||
|
||||
const Value v = evaluate_leaf(pos, node, leafDepth);
|
||||
|
||||
BackpropValues backprops{};
|
||||
backprops.numVisits = 1; // playout counts as a visit
|
||||
backprops.actionValue += value_to_reward(v);
|
||||
backprops.actionValueWeight += normalWeight;
|
||||
|
||||
// Bookkeeping for raw eval
|
||||
node.leafSearchEval = v;
|
||||
node.leafSearchDepth = leafDepth;
|
||||
|
||||
// Local backprop because normal backprop handles only the
|
||||
// nodes starting from the parent of this one.
|
||||
node.numVisits = backprops.numVisits;
|
||||
node.actionValue += backprops.actionValue;
|
||||
node.actionValueWeight += backprops.actionValueWeight;
|
||||
|
||||
return backprops;
|
||||
}
|
||||
|
||||
|
||||
// expand_node_and_do_playout() : expand a node and do at least one playout.
|
||||
// May do more "playouts" if there are terminals as those are "played out" immediately.
|
||||
// Returns what needs to be backpropagated.
|
||||
|
||||
BackpropValues expand_node_and_do_playout( Position& pos,
|
||||
MCTSNode& node,
|
||||
Depth leafDepth,
|
||||
float explorationFactor)
|
||||
{
|
||||
assert(node.posKey == pos.key()); // node must match the position
|
||||
assert(node.is_leaf()); // otherwise already expanded
|
||||
assert(node.numChildren == 0); // leafs have no children
|
||||
assert(!node.isTerminal); // terminals cannot be expanded
|
||||
assert(node.numVisits == 1); // we expect it to have the "playout visit". Fake visit for the root.
|
||||
assert(node.leafSearchDepth != DEPTH_NONE);
|
||||
assert(node.leafSearchEval != VALUE_NONE);
|
||||
|
||||
debug << "Expanding and playing out: " << pos.fen() << endl;
|
||||
|
||||
Move moves[MAX_MOVES];
|
||||
const int moveCount = generate_moves_ordered(pos, node, leafDepth, moves);
|
||||
|
||||
assert(moveCount > 0);
|
||||
|
||||
node.children = std::make_unique<MCTSNode[]>(moveCount);
|
||||
node.numChildren = moveCount;
|
||||
|
||||
int numTerminals = 0;
|
||||
BackpropValues backprops{};
|
||||
|
||||
float prior = value_to_reward(node.leafSearchEval);
|
||||
|
||||
// Note that prior is attenuated for later moves - we rely on move ordering.
|
||||
// Attenuate more at higher plies, where we have better move ordering.
|
||||
|
||||
const float priorAttenuation = 1.0f - std::min((ply - 1) / 100.0f, 0.05f);
|
||||
for (int i = 0; i < moveCount; ++i)
|
||||
{
|
||||
// Setup the child
|
||||
MCTSNode& child = node.children[i];
|
||||
child.prevMove = moves[i];
|
||||
child.childId = i;
|
||||
child.parent = &node;
|
||||
|
||||
debug << "Expanding move " << i+1 << " out of " << moveCount << ": " << pos.fen() << endl;
|
||||
|
||||
// We enter the child's position
|
||||
do_move(pos, node, child);
|
||||
child.posKey = pos.key();
|
||||
|
||||
const Value terminalValue = terminal_value(pos);
|
||||
if (terminalValue != VALUE_NONE)
|
||||
{
|
||||
// if it's a terminal then "play it out"
|
||||
child.isTerminal = true;
|
||||
child.prior = value_to_reward(terminalValue);
|
||||
child.numVisits = 1;
|
||||
child.actionValue = child.prior * terminalWeight;
|
||||
child.actionValueWeight = terminalWeight;
|
||||
child.leafSearchEval = terminalValue;
|
||||
child.leafSearchDepth = terminalEvalDepth;
|
||||
|
||||
numTerminals += 1;
|
||||
numPlayouts += 1;
|
||||
}
|
||||
else
|
||||
{
|
||||
// Otherwise we just note the prior (policy)
|
||||
child.prior = 1.0f - prior;
|
||||
child.actionValue = child.prior * priorWeight;
|
||||
child.actionValueWeight = priorWeight;
|
||||
}
|
||||
|
||||
undo_move(pos);
|
||||
|
||||
// Accumulate the policies to backprop
|
||||
backprops.actionValue += child.actionValue;
|
||||
backprops.actionValueWeight += child.actionValueWeight;
|
||||
|
||||
// Reduce the prior for the next move
|
||||
prior *= priorAttenuation;
|
||||
}
|
||||
|
||||
if (numTerminals == 0)
|
||||
{
|
||||
// If no terminals then we do one playout on the best child
|
||||
MCTSNode& bestChild = node.get_best_child(explorationFactor);
|
||||
do_move(pos, node, bestChild);
|
||||
|
||||
backprops.numVisits += 1;
|
||||
|
||||
auto playoutBackprops = do_playout(pos, bestChild, leafDepth);
|
||||
backprops.numVisits += playoutBackprops.numVisits;
|
||||
backprops.actionValue += playoutBackprops.actionValue;
|
||||
backprops.actionValueWeight += playoutBackprops.actionValueWeight;
|
||||
|
||||
undo_move(pos);
|
||||
}
|
||||
else
|
||||
{
|
||||
// If there are any terminals we don't do more playouts
|
||||
backprops.numVisits += numTerminals;
|
||||
}
|
||||
|
||||
// Local backprop because normal backprop handles only the
|
||||
// nodes starting from the parent of this one
|
||||
backprops.flip_side();
|
||||
|
||||
node.actionValue = backprops.actionValue;
|
||||
node.actionValueWeight = backprops.actionValueWeight;
|
||||
node.numVisits = backprops.numVisits;
|
||||
|
||||
return backprops;
|
||||
}
|
||||
|
||||
|
||||
// do_move() does a move and updates the stack
|
||||
|
||||
void do_move(Position& pos, MCTSNode& parentNode, MCTSNode& childNode) {
|
||||
|
||||
assert(ply < MAX_PLY);
|
||||
assert(!parentNode.is_leaf());
|
||||
assert(&parentNode.children[childNode.childId] == &childNode);
|
||||
assert(parentNode.posKey == pos.key());
|
||||
|
||||
const Move move = childNode.prevMove;
|
||||
|
||||
stack[ply].currentMove = move;
|
||||
stack[ply].inCheck = pos.checkers();
|
||||
stack[ply].continuationHistory =
|
||||
&(
|
||||
pos.this_thread()->continuationHistory
|
||||
[stack[ply].inCheck]
|
||||
[pos.capture_or_promotion(move)]
|
||||
[pos.moved_piece(move)]
|
||||
[to_sq(move)]
|
||||
);
|
||||
stack[ply].staticEval = parentNode.leafSearchEval;
|
||||
stack[ply].moveCount = childNode.childId + 1;
|
||||
|
||||
pos.do_move(move, states[ply]);
|
||||
|
||||
// The first time around we don't have posKey set yet,
|
||||
// because we need to do the move first.
|
||||
assert(childNode.posKey == 0 || childNode.posKey == pos.key());
|
||||
|
||||
ply += 1;
|
||||
|
||||
if (ply > maximumPly)
|
||||
maximumPly = ply;
|
||||
}
|
||||
|
||||
|
||||
// undo_move() undoes a move and pops the stack
|
||||
|
||||
void undo_move(Position& pos) {
|
||||
assert(ply > 1);
|
||||
|
||||
ply -= 1;
|
||||
|
||||
pos.undo_move(stack[ply].currentMove);
|
||||
}
|
||||
|
||||
|
||||
// create_new_root() inits a root from the given position
|
||||
|
||||
void create_new_root(Position& pos) {
|
||||
rootNode = MCTSNode{};
|
||||
rootNode.posKey = pos.key();
|
||||
rootNode.isTerminal = MoveList<LEGAL>(pos).size() == 0;
|
||||
}
|
||||
|
||||
|
||||
void init_for_mcts_search(Position& pos) {
|
||||
std::memset(stack - 7, 0, 10 * sizeof(Stack));
|
||||
|
||||
auto th = pos.this_thread();
|
||||
|
||||
// stack + 0 also needs to be initialized because we start from ply = 1
|
||||
for (int i = 7; i >= 0; --i)
|
||||
(stack - i)->continuationHistory = &th->continuationHistory[0][0][NO_PIECE][0]; // Use as a sentinel
|
||||
|
||||
for (int i = 1; i <= MAX_PLY; ++i)
|
||||
(stack + i)->ply = i;
|
||||
|
||||
int ct = int(Options["Contempt"]) * PawnValueEg / 100; // From centipawns
|
||||
Color us = pos.side_to_move();
|
||||
|
||||
// In analysis mode, adjust contempt in accordance with user preference
|
||||
if (Limits.infinite || Options["UCI_AnalyseMode"])
|
||||
ct = Options["Analysis Contempt"] == "Off" ? 0
|
||||
: Options["Analysis Contempt"] == "Both" ? ct
|
||||
: Options["Analysis Contempt"] == "White" && us == BLACK ? -ct
|
||||
: Options["Analysis Contempt"] == "Black" && us == WHITE ? -ct
|
||||
: ct;
|
||||
|
||||
// Evaluation score is from the white point of view
|
||||
th->contempt = (us == WHITE ? make_score(ct, ct / 2)
|
||||
: -make_score(ct, ct / 2));
|
||||
|
||||
create_new_root(pos);
|
||||
|
||||
ply = 1;
|
||||
maximumPly = ply;
|
||||
numPlayouts = 0;
|
||||
}
|
||||
};
|
||||
|
||||
|
||||
// search_mcts() : this is the main function of the MonteCarloTreeSearch class
|
||||
|
||||
ValueAndPV search_mcts( Position& pos,
|
||||
uint64_t numPlayouts,
|
||||
Depth leafDepth,
|
||||
float explorationFactor)
|
||||
{
|
||||
MonteCarloTreeSearch mcts{};
|
||||
return mcts.search_new(pos, numPlayouts, leafDepth, explorationFactor);
|
||||
}
|
||||
|
||||
|
||||
// search_mcts_multipv() : use this for multiPV
|
||||
|
||||
std::vector<MctsContinuation> search_mcts_multipv( Position& pos,
|
||||
uint64_t numPlayouts,
|
||||
Depth leafDepth,
|
||||
float explorationFactor)
|
||||
{
|
||||
MonteCarloTreeSearch mcts{};
|
||||
mcts.search_new(pos, numPlayouts, leafDepth, explorationFactor);
|
||||
|
||||
return mcts.get_all_continuations();
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
} // namespace Stockfish
|
||||
|
|
22
src/search.h
22
src/search.h
|
@ -119,6 +119,28 @@ using ValueAndPV = std::pair<Value, std::vector<Move>>;
|
|||
ValueAndPV qsearch(Position& pos);
|
||||
ValueAndPV search(Position& pos, int depth_, size_t multiPV = 1, uint64_t nodesLimit = 0);
|
||||
|
||||
namespace MCTS {
|
||||
|
||||
struct MctsContinuation {
|
||||
std::uint64_t numVisits;
|
||||
Value value;
|
||||
float actionValue;
|
||||
std::vector<Move> pv;
|
||||
};
|
||||
|
||||
ValueAndPV search_mcts(
|
||||
Position& pos,
|
||||
std::uint64_t nodes,
|
||||
Depth leafDepth,
|
||||
float explorationFactor);
|
||||
|
||||
std::vector<MctsContinuation> search_mcts_multipv(
|
||||
Position& pos,
|
||||
std::uint64_t numPlayouts,
|
||||
Depth leafDepth,
|
||||
float explorationFactor);
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
} // namespace Stockfish
|
||||
|
|
|
@ -767,7 +767,7 @@ namespace Stockfish::Tools
|
|||
else if (token == "min_depth")
|
||||
is >> params.search_depth_min;
|
||||
else if (token == "max_depth")
|
||||
is >> params.search_depth_min;
|
||||
is >> params.search_depth_max;
|
||||
else if (token == "nodes")
|
||||
is >> params.nodes;
|
||||
else if (token == "count")
|
||||
|
|
29
src/uci.cpp
29
src/uci.cpp
|
@ -269,6 +269,34 @@ void search_cmd(Position& pos, istringstream& is)
|
|||
cout << endl;
|
||||
}
|
||||
|
||||
void search_mcts_cmd(Position& pos, istringstream& is)
|
||||
{
|
||||
string token;
|
||||
int nodes = 1000;
|
||||
int leafDepth = 3;
|
||||
float explorationFactor = 0.25f;
|
||||
while (is >> token)
|
||||
{
|
||||
if (token == "nodes")
|
||||
is >> nodes;
|
||||
if (token == "leaf_depth")
|
||||
is >> leafDepth;
|
||||
if (token == "exploration_factor")
|
||||
is >> explorationFactor;
|
||||
}
|
||||
|
||||
cout << "search nodes = " << nodes << " , leaf_depth = " << leafDepth << " :\n";
|
||||
auto continuations = Search::MCTS::search_mcts_multipv(pos, nodes, leafDepth, explorationFactor);
|
||||
for (auto&& [numVisits, value, actionValue, pv] : continuations)
|
||||
{
|
||||
cout << "NumVisits = " << numVisits << " , Value = " << UCI::value(value) << " , ActionValue = " << actionValue << " , PV = ";
|
||||
for (auto m : pv)
|
||||
cout << UCI::move(m, false) << " ";
|
||||
cout << endl;
|
||||
}
|
||||
cout << endl;
|
||||
}
|
||||
|
||||
/// UCI::loop() waits for a command from stdin, parses it and calls the appropriate
|
||||
/// function. Also intercepts EOF from stdin to ensure gracefully exiting if the
|
||||
/// GUI dies unexpectedly. When called with some command line arguments, e.g. to
|
||||
|
@ -344,6 +372,7 @@ void UCI::loop(int argc, char* argv[]) {
|
|||
|
||||
// Command to call qsearch(),search() directly for testing
|
||||
else if (token == "qsearch") qsearch_cmd(pos);
|
||||
else if (token == "search_mcts") search_mcts_cmd(pos, is);
|
||||
else if (token == "search") search_cmd(pos, is);
|
||||
else if (token == "tasktest")
|
||||
{
|
||||
|
|
Loading…
Reference in New Issue