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/********************* */
/*! \file sygus_grammar_red.h
** \verbatim
** Top contributors (to current version):
** Andrew Reynolds, Mathias Preiner
** This file is part of the CVC4 project.
** Copyright (c) 2009-2021 by the authors listed in the file AUTHORS
** in the top-level source directory and their institutional affiliations.
** All rights reserved. See the file COPYING in the top-level source
** directory for licensing information.\endverbatim
**
** \brief sygus_grammar_red
**/
#include "cvc4_private.h"
#ifndef CVC4__THEORY__QUANTIFIERS__SYGUS_GRAMMAR_RED_H
#define CVC4__THEORY__QUANTIFIERS__SYGUS_GRAMMAR_RED_H
#include <map>
#include <vector>
#include "expr/node.h"
namespace cvc5 {
namespace theory {
namespace quantifiers {
class TermDbSygus;
/** SygusRedundantCons
*
* This class computes the subset of indices of the constructors of a sygus type
* that are redundant. To use this class, first call initialize( qe, tn ),
* where tn is a sygus tn. Then, use getRedundant and/or isRedundant to get the
* indicies of the constructors of tn that are redundant.
*/
class SygusRedundantCons
{
public:
SygusRedundantCons() {}
~SygusRedundantCons() {}
/** register type tn
*
* qe : pointer to the quantifiers engine,
* tn : the (sygus) type to compute redundant constructors for
*/
void initialize(TermDbSygus* tds, TypeNode tn);
/** Get the indices of the redundant constructors of the register type */
void getRedundant(std::vector<unsigned>& indices);
/**
* This function returns true if the i^th constructor of the registered type
* is redundant.
*/
bool isRedundant(unsigned i);
private:
/** the registered type */
TypeNode d_type;
/** redundant status
*
* For each constructor, status indicating whether the constructor is
* redundant, where:
*
* 0 : not redundant,
* 1 : redundant since another constructor can be used to construct values for
* this constructor.
*
* For example, for grammar:
* A -> C > B | B < C | not D
* B -> x | y
* C -> 0 | 1 | C+C
* D -> B >= C
* If A is register with this class, then we store may store { 0, 1, 0 },
* noting that the second constructor of A can be simulated with the first.
* Notice that the third constructor is not considered redundant.
*/
std::vector<int> d_sygus_red_status;
/**
* Map from constructor indices to the generic term for that constructor,
* where the generic term for a constructor is the (canonical) term returned
* by a call to TermDbSygus::mkGeneric.
*/
std::map<unsigned, Node> d_gen_terms;
/**
* Map from the rewritten form of generic terms for constructors of the
* registered type to their corresponding constructor index.
*/
std::map<Node, unsigned> d_gen_cons;
/** get generic list
*
* This function constructs all well-typed variants of a term of the form
* op( x1, ..., xn )
* where op is the builtin operator for dt[c], and xi = pre[i] for i=1,...,n.
*
* It constructs a list of terms of the form g * sigma, where sigma
* is an automorphism on { x1...xn } such that for all xi -> xj in sigma,
* the type for arguments i and j of dt[c] are the same. We store this
* list of terms in terms.
*
* This function recurses on the arguments of g, index is the current argument
* we are processing, and pre stores the current arguments of
*
* For example, for a sygus grammar
* A -> and( A, A, B )
* B -> false
* passing arguments such that g=and( x1, x2, x3 ) to this function will add:
* and( x1, x2, x3 ) and and( x2, x1, x3 )
* to terms.
*/
void getGenericList(TermDbSygus* tds,
const DType& dt,
unsigned c,
unsigned index,
std::map<int, Node>& pre,
std::vector<Node>& terms);
};
} // namespace quantifiers
} // namespace theory
} // namespace cvc5
#endif /* CVC4__THEORY__QUANTIFIERS__SYGUS_GRAMMAR_RED_H */
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