From 6c2ec23c8d74bc42fd7e4a9d67da3adefe8f0332 Mon Sep 17 00:00:00 2001
From: Theodore Turocy <ted.turocy@gmail.com>
Date: Wed, 11 Feb 2026 14:02:18 +0000
Subject: [PATCH] Restrict search space for `enumpoly` to be strictly interior.

This shrinks the search space for searching for equilibria on a
given support to be in the interior of the simplex (rather than
including the boundaries as before).

This solves the behaviour noted in #756, in which degenerate situations
which required a solution to be on
the boundary would be very slow as it tried
to approach the solution on the boundary.
---
 src/solvers/enumpoly/efgpoly.cc | 4 ++--
 src/solvers/enumpoly/nfgpoly.cc | 4 ++--
 src/solvers/enumpoly/poly.h     | 6 +++++-
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/solvers/enumpoly/efgpoly.cc b/src/solvers/enumpoly/efgpoly.cc
index e30210949..ad7ada9c2 100644
--- a/src/solvers/enumpoly/efgpoly.cc
+++ b/src/solvers/enumpoly/efgpoly.cc
@@ -161,8 +161,8 @@ std::list<MixedBehaviorProfile<double>> SolveSupport(const BehaviorSupportProfil
 
   // set up the rectangle of search
   Vector<double> bottoms(data.space->GetDimension()), tops(data.space->GetDimension());
-  bottoms = 0;
-  tops = 1;
+  bottoms = 1e-12;
+  tops = 1 - 1e-12;
 
   PolynomialSystemSolver solver(equations);
   std::list<Vector<double>> roots;
diff --git a/src/solvers/enumpoly/nfgpoly.cc b/src/solvers/enumpoly/nfgpoly.cc
index 3334b7de7..a77d730f5 100644
--- a/src/solvers/enumpoly/nfgpoly.cc
+++ b/src/solvers/enumpoly/nfgpoly.cc
@@ -111,8 +111,8 @@ EnumPolyStrategySupportSolve(const StrategySupportProfile &support, bool &is_sin
   const PolynomialSystem<double> equations = ConstructEquations(space, support, strategy_poly);
 
   Vector<double> bottoms(space->GetDimension()), tops(space->GetDimension());
-  bottoms = 0;
-  tops = 1;
+  bottoms = 1e-12;
+  tops = 1 - 1e-12;
   PolynomialSystemSolver solver(equations);
   is_singular = false;
   std::list<Vector<double>> roots;
diff --git a/src/solvers/enumpoly/poly.h b/src/solvers/enumpoly/poly.h
index 2cc2db670..eb3390c6f 100644
--- a/src/solvers/enumpoly/poly.h
+++ b/src/solvers/enumpoly/poly.h
@@ -375,7 +375,11 @@ template <class T> class Polynomial {
     });
   }
   [[nodiscard]] const std::vector<Monomial<T>> &GetTerms() const noexcept { return m_terms; }
-  bool IsZero() const noexcept { return m_terms.empty(); }
+  bool IsZero() const noexcept
+  {
+    return m_terms.empty() || std::all_of(m_terms.begin(), m_terms.end(),
+                                          [](const auto &mono) { return mono.IsZero(); });
+  }
   bool IsConstant() const noexcept
   {
     return m_terms.size() == 1 && m_terms.front().TotalDegree() == 0;