Pre-construct polynomial representations of probabilities.

gambitproject · Jul 18, 2024 · 60b6218 · 60b6218
1 parent 362d09f
commit 60b6218
Showing 1 changed file with 17 additions and 33 deletions.
diff --git a/src/solvers/enumpoly/nfgpoly.cc b/src/solvers/enumpoly/nfgpoly.cc
@@ -42,15 +42,15 @@ class PolEnumModule {
   // in a solution is inferred by the sum-to-one constraint.
   std::map<GameStrategy, int> strategy_vars;
   std::list<GameStrategy> strategy_omit;
+  // The polynomial representation of each strategy probability, substituting in
+  // the sum-to-one equation for the probability of the last strategy for each player
+  std::map<GameStrategy, gPoly<double>> strategy_poly;
   gSpace Space;
   term_order Lex;
   int num_vars;
   List<MixedStrategyProfile<double>> solutions;
   bool is_singular{false};
 
-  // p_i_j as a gPoly, with last prob in terms of previous probs
-  gPoly<double> Prob(const GameStrategy &strategy) const;
-
   // equation for when player i sets strat1 = strat2
   // with last probs for each player substituted out.
   gPoly<double> IndifferenceEquation(const GameStrategy &s1, const GameStrategy &s2) const;
@@ -81,14 +81,25 @@ PolEnumModule::PolEnumModule(const StrategySupportProfile &S)
     num_vars(support.MixedProfileLength() - S.GetGame()->NumPlayers())
 {
   int index = 1;
+  Vector<int> exps(num_vars);
+
   for (auto player : support.GetGame()->GetPlayers()) {
     auto strategies = support.GetStrategies(player);
+    exps = 0;
+    gPoly<double> residual(&Space, gMono<double>(1, exp_vect(&Space, exps)), &Lex);
     for (auto strategy : strategies) {
       if (strategy != strategies.back()) {
-        strategy_vars[strategy] = index++;
+        strategy_vars[strategy] = index;
+        exps = 0;
+        exps[index] = 1;
+        auto poly = gPoly<double>(&Space, gMono<double>(1, exp_vect(&Space, exps)), &Lex);
+        strategy_poly.emplace(strategy, poly);
+        residual -= strategy_poly.at(strategy);
+        index++;
       }
       else {
         strategy_omit.push_back(strategy);
+        strategy_poly.emplace(strategy, residual);
       }
     }
   }
@@ -126,33 +137,6 @@ int PolEnumModule::SaveSolutions(const List<Vector<double>> &list)
   return solutions.size();
 }
 
-gPoly<double> PolEnumModule::Prob(const GameStrategy &strategy) const
-{
-  gPoly<double> equation(&Space, &Lex);
-  Vector<int> exps(num_vars);
-
-  auto var_mapping = strategy_vars.find(strategy);
-
-  if (var_mapping != strategy_vars.end()) {
-    exps = 0;
-    exps[var_mapping->second] = 1;
-    equation += gPoly<double>(&Space, gMono<double>(1, exp_vect(&Space, exps)), &Lex);
-  }
-  else {
-    for (auto strat : support.GetStrategies(strategy->GetPlayer())) {
-      var_mapping = strategy_vars.find(strat);
-      if (var_mapping != strategy_vars.end()) {
-        exps = 0;
-        exps[var_mapping->second] = 1;
-        equation += gPoly<double>(&Space, gMono<double>(-1, exp_vect(&Space, exps)), &Lex);
-      }
-    }
-    exps = 0;
-    equation += gPoly<double>(&Space, gMono<double>(1, exp_vect(&Space, exps)), &Lex);
-  }
-  return equation;
-}
-
 gPoly<double> PolEnumModule::IndifferenceEquation(const GameStrategy &s1,
                                                   const GameStrategy &s2) const
 {
@@ -162,7 +146,7 @@ gPoly<double> PolEnumModule::IndifferenceEquation(const GameStrategy &s1,
     gPoly<double> term(&Space, 1, &Lex);
     for (auto player : support.GetGame()->GetPlayers()) {
       if (player != s1->GetPlayer()) {
-        term *= Prob((*A)->GetStrategy(player));
+        term *= strategy_poly.at((*A)->GetStrategy(player));
       }
     }
     term *= (*A)->GetPayoff(s1->GetPlayer()) - (*B)->GetPayoff(s1->GetPlayer());
@@ -185,7 +169,7 @@ void PolEnumModule::IndifferenceEquations(gPolyList<double> &equations) const
 void PolEnumModule::LastActionProbPositiveInequalities(gPolyList<double> &equations) const
 {
   for (auto strategy : strategy_omit) {
-    equations += Prob(strategy);
+    equations += strategy_poly.at(strategy);
   }
 }