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Fix symbolic counting #57

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merged 4 commits into from
Apr 29, 2024
Merged

Fix symbolic counting #57

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3980c58
Use a pseudoboolean encoding for symbolic counting constraints
balasub Apr 29, 2024
f4f3f99
Bump setup-dotnet from v2 to v4
balasub Apr 29, 2024
f46b3c3
Bump setup-dotnet from v2 to v4
balasub Apr 29, 2024
2e2107f
Temporarily remove macos-latest from build
balasub Apr 29, 2024
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2 changes: 1 addition & 1 deletion .github/workflows/build.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ jobs:
steps:
- uses: actions/checkout@v3
- name: Setup .NET
uses: actions/setup-dotnet@v2
uses: actions/setup-dotnet@v4
with:
dotnet-version: |
6.x
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4 changes: 2 additions & 2 deletions .github/workflows/dotnet.yml
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Expand Up @@ -11,11 +11,11 @@ jobs:
runs-on: ${{ matrix.os }}
strategy:
matrix:
os: [ ubuntu-latest, windows-latest, macOS-latest ]
os: [ ubuntu-latest, windows-latest ]
steps:
- uses: actions/checkout@v3
- name: Setup .NET
uses: actions/setup-dotnet@v2
uses: actions/setup-dotnet@v4
with:
dotnet-version: |
6.x
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80 changes: 50 additions & 30 deletions Src/Core/Solver/Execution/TermEncIndex.cs
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Expand Up @@ -336,47 +336,67 @@ public Z3Expr GetTerm(Term t, out Term normalizedTerm, SymExecuter facts = null)

private Z3Expr GetSymCountExpr(SymExecuter facts, Term x, IEnumerable<Z3Expr> ch)
{
// 1. Add the base count
List<Z3ArithExpr> exprs = new List<Z3ArithExpr>();
exprs.Add((Z3ArithExpr)ch.ElementAt(0));

// 2. Create an ITE for each term.
// If a term's constraints are satisfied, the count is incremented by 1
int index = ((int)((Rational)((BaseCnstSymb)x.Args[1].Symbol).Raw).Numerator);
Term comprTerms = facts.GetSymbolicCountTerm(x.Args[2], index);
List<Z3BoolExpr> allBoolExprs = new List<Z3BoolExpr>();
for (int i = 2; i < comprTerms.Args.Count(); i++)

int numTerms = comprTerms.Args.Count() - 2;
Z3Expr[] termExprs = new Z3Expr[numTerms];
Z3BoolExpr[] boolExprs = new Z3BoolExpr[numTerms];
Term normalized;

for (int i = 0; i < comprTerms.Args.Count() - 2; i++)
{
Z3BoolExpr boolExpr = facts.GetSideConstraints(comprTerms.Args[i]);
allBoolExprs.Add(boolExpr);
exprs.Add((Z3ArithExpr)facts.Solver.Context.MkITE(boolExpr,
facts.Solver.Context.MkInt(1),
facts.Solver.Context.MkInt(0)));
var e1Term = comprTerms.Args[i + 2].Args[0];
termExprs[i] = GetTerm(e1Term, out normalized, facts);
boolExprs[i] = facts.GetSideConstraints(comprTerms.Args[i + 2]); // TODO: check if we need comprTerms.Args[i + 2].Args[0] here
}

// 3. The equality between any two terms decrements the count by 1
Term normalized;
for (int i = 0; i < allBoolExprs.Count; i++)
int numCoeffs = (2 * numTerms) - 1;
int[] coeffs = new int[numCoeffs];
Z3BoolExpr[] args = new Z3BoolExpr[numCoeffs];
Z3BoolExpr[] pbTerms = new Z3BoolExpr[numTerms + 1];

for (int i = 0; i < numTerms; i++)
{
for (int j = i + 1; j < allBoolExprs.Count; j++)
coeffs[i] = 1;
args[i] = boolExprs[i];
}

for (int i = 0; i < numTerms - 1; i++)
{
int currIndex = numTerms + i;
Z3BoolExpr currExpr = null;
List<Z3BoolExpr> currExprs = new List<Z3BoolExpr>();
for (int j = i + 1; j < numTerms; j++)
{
var e1Term = comprTerms.Args[i + 2].Args[0];
var e2Term = comprTerms.Args[j + 2].Args[0];
currExpr = facts.Solver.Context.MkEq(termExprs[i], termExprs[j]);
currExpr = facts.Solver.Context.MkAnd(currExpr, boolExprs[i]);
currExpr = facts.Solver.Context.MkAnd(currExpr, boolExprs[j]);
currExprs.Add(currExpr);
}

var e1Enc = GetTerm(e1Term, out normalized, facts);
var e2Enc = GetTerm(e2Term, out normalized, facts);
coeffs[currIndex] = -1;
args[currIndex] = facts.Solver.Context.MkOr(currExprs);
}

var e1 = facts.Solver.Context.MkEq(e1Enc, e2Enc);
var e2 = allBoolExprs.ElementAt(i);
var e3 = allBoolExprs.ElementAt(j);
var e4 = facts.Solver.Context.MkAnd(new Z3BoolExpr[] { e1, e2, e3 });
exprs.Add((Z3ArithExpr)facts.Solver.Context.MkITE(e4,
facts.Solver.Context.MkInt(-1),
facts.Solver.Context.MkInt(0)));
}
for (int i = 0; i < numTerms + 1; i++)
{
pbTerms[i] = facts.Solver.Context.MkPBEq(coeffs, args, i);
}

return facts.Solver.Context.MkAdd(exprs);
return MakeCardConstraint(facts, pbTerms, numTerms);
}

private Z3ArithExpr MakeCardConstraint(SymExecuter facts, Z3BoolExpr[] constraints, int index)
{
if (index == 0)
{
return (Z3ArithExpr)facts.Solver.Context.MkITE(constraints[index], facts.Solver.Context.MkInt(index), facts.Solver.Context.MkInt(-1));
}
else
{
return (Z3ArithExpr)facts.Solver.Context.MkITE(constraints[index], facts.Solver.Context.MkInt(index), MakeCardConstraint(facts, constraints, index - 1));
}
}

public void Debug_Print()
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