/*
* The method Skolemize performs best-effort skolemization of the input expression expr.
* If polarity == Polarity.Negative, a quantifier F embedded in expr is skolemized
* provided it can be proved that F is a forall quantifier in the NNF version of expr.
* If polarity == Polarity.Positive, a quantifier F embedded in expr is skolemized
* provided it can be proved that F is an exists quantifier in the NNF version of expr.
*
* Factorization is performed on the resulting expression.
*/
public static VCExpr Skolemize(QuantifierInstantiationEngine qiEngine, Polarity polarity, VCExpr vcExpr)
{
var skolemizer = new Skolemizer(qiEngine, polarity, vcExpr);
var skolemizedExpr = skolemizer.Mutate(vcExpr, true);
return(Factorizer.Factorize(qiEngine, QuantifierCollector.Flip(polarity), skolemizedExpr));
}
public static HashSet <VCExprVar> CollectBindings(QuantifierInstantiationEngine qiEngine, VCExpr vcExpr)
{
var bindingCollector = new BindingCollector(qiEngine);
bindingCollector.Traverse(vcExpr, true);
return(bindingCollector.bindings);
}
private LambdaInstanceCollector(QuantifierInstantiationEngine qiEngine)
{
this.qiEngine = qiEngine;
this.lambdaFunctions = new HashSet <Function>();
this.instances = new HashSet <VCExprNAry>();
this.instancesOnStack = new Stack <VCExprNAry>();
}
public static VCExpr Instantiate(Implementation impl, VCExpressionGenerator vcExprGen, Boogie2VCExprTranslator exprTranslator, VCExpr vcExpr)
{
if (!InstantiationSourceChecker.HasInstantiationSources(impl))
{
return(vcExpr);
}
var qiEngine = new QuantifierInstantiationEngine(vcExprGen, exprTranslator);
return(qiEngine.Execute(impl, vcExpr));
}
public static Dictionary <Function, HashSet <List <VCExpr> > > CollectInstances(QuantifierInstantiationEngine qiEngine, VCExpr vcExpr)
{
var lambdaInstanceCollector = new LambdaInstanceCollector(qiEngine);
lambdaInstanceCollector.Traverse(vcExpr, true);
var lambdaFunctionToInstances = new Dictionary <Function, HashSet <List <VCExpr> > >();
foreach (var instance in lambdaInstanceCollector.instances)
{
var function = (instance.Op as VCExprBoogieFunctionOp).Func;
if (!lambdaFunctionToInstances.ContainsKey(function))
{
lambdaFunctionToInstances[function] = new HashSet <List <VCExpr> >(new ListComparer <VCExpr>());
}
lambdaFunctionToInstances[function].Add(instance.UniformArguments.ToList());
}
return(lambdaFunctionToInstances);
}
private BindingCollector(QuantifierInstantiationEngine qiEngine)
{
this.qiEngine = qiEngine;
this.bindings = new HashSet <VCExprVar>();
}
private Factorizer(QuantifierInstantiationEngine qiEngine, Polarity polarity, VCExpr vcExpr) : base(qiEngine.vcExprGen)
{
this.qiEngine = qiEngine;
this.quantifiers = QuantifierCollector.CollectQuantifiers(vcExpr, polarity);
}
public static VCExpr Factorize(QuantifierInstantiationEngine qiEngine, Polarity polarity, VCExpr vcExpr)
{
var factorizer = new Factorizer(qiEngine, polarity, vcExpr);
return(factorizer.Mutate(vcExpr, true));
}
private Skolemizer(QuantifierInstantiationEngine qiEngine, Polarity polarity, VCExpr vcExpr) : base(qiEngine.vcExprGen)
{
this.qiEngine = qiEngine;
this.quantifiers = QuantifierCollector.CollectQuantifiers(vcExpr, polarity);
this.bound = new Dictionary <VCExprVar, VCExpr>();
}
