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z3/src/sat/smt/q_model_fixer.h
2022-08-05 18:11:46 +03:00

129 lines
4 KiB
C++

/*++
Copyright (c) 2020 Microsoft Corporation
Module Name:
q_model_fixer.h
Abstract:
Model-based quantifier instantiation model-finder plugin
Author:
Nikolaj Bjorner (nbjorner) 2020-10-02
Notes:
Derives from smt/smt_model_finder.cpp
Contains exclusively functionality that adjusts a model to make it
easier to satisfy relevant universally quantified literals.
--*/
#pragma once
#include "sat/smt/sat_th.h"
#include "solver/solver.h"
#include "model/model_macro_solver.h"
#include "qe/mbp/mbp_plugin.h"
namespace euf {
class solver;
}
namespace q {
class solver;
typedef obj_hashtable<func_decl> func_decl_set;
class projection_function {
protected:
ast_manager& m;
public:
projection_function(ast_manager& m) : m(m) {}
virtual ~projection_function() = default;
virtual expr* mk_lt(expr* a, expr* b) = 0;
expr* mk_le(expr* a, expr* b) { return m.mk_not(mk_lt(b, a)); }
virtual bool operator()(expr* a, expr* b) const = 0;
};
/**
* meta-data for a projection function for f at index idx (indexed-decl).
* The meta-data contains the set of model values that the idx'th argument of f
* has and a map from model values to terms and back.
*/
struct projection_meta_data {
projection_meta_data(ast_manager& m) : values(m) {}
expr_ref_vector values;
obj_map<expr, expr*> v2t;
obj_map<expr, expr*> t2v;
};
struct indexed_decl {
func_decl* f;
unsigned idx;
indexed_decl() : f(nullptr), idx(0) {}
indexed_decl(func_decl* f, unsigned idx): f(f), idx(idx) {}
struct hash { unsigned operator()(indexed_decl const& d) const { return d.idx + d.f->hash(); } };
struct eq { bool operator()(indexed_decl const& a, indexed_decl const& b) const { return a.idx == b.idx && a.f == b.f; } };
};
class model_fixer : public quantifier2macro_infos {
euf::solver& ctx;
solver& m_qs;
ast_manager& m;
obj_map<quantifier, quantifier_macro_info*> m_q2info;
func_decl_dependencies m_dependencies;
obj_map<sort, projection_function*> m_projections;
map<indexed_decl, projection_meta_data*, indexed_decl::hash, indexed_decl::eq> m_projection_data;
scoped_ptr_vector<projection_meta_data> m_projection_pinned;
void add_projection_functions(model& mdl, ptr_vector<quantifier> const& qs);
void add_projection_functions(model& mdl, func_decl* f);
expr_ref add_projection_function(model& mdl, func_decl* f, unsigned idx);
void collect_partial_functions(ptr_vector<quantifier> const& qs, func_decl_set& fns);
projection_function* get_projection(sort* srt);
projection_meta_data* get_projection_data(func_decl* f, unsigned idx) const {
projection_meta_data* r = nullptr;
m_projection_data.find(indexed_decl(f, idx), r);
return r;
}
public:
model_fixer(euf::solver& ctx, solver& qs);
/**
* Update model in order to best satisfy quantifiers.
* For the array property fragment, update the model
* such that the range of functions behaves monotonically
* based on regions over the inputs.
*/
void operator()(model& mdl);
quantifier_macro_info* operator()(quantifier* q) override;
/*
* Create a constraint that restricts the possible values of t to a finite set of values.
* Add value constraints to solver?
*/
expr_ref restrict_arg(app* t, unsigned i);
/*
* Create inequality constraints for the i'th argument of t based on the current model.
*/
void invert_arg(app* t, unsigned i, expr* value, expr_ref_vector& lits);
/*
* Replace term that contains uninterpreted function over free variables with a ground term.
*/
expr* invert_app(app* t, expr* value);
};
}