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77 lines
1.8 KiB
C++
77 lines
1.8 KiB
C++
/*++
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Copyright (c) 2006 Microsoft Corporation
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Module Name:
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elim_bounds2.h
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Abstract:
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<abstract>
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Author:
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Leonardo de Moura (leonardo) 2008-06-28.
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Revision History:
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--*/
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#ifndef ELIM_BOUNDS2_H_
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#define ELIM_BOUNDS2_H_
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#include "ast/ast.h"
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#include "ast/arith_decl_plugin.h"
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#include "ast/rewriter/rewriter.h"
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/**
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\brief Functor for eliminating irrelevant bounds in quantified formulas.
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Example:
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(forall (x Int) (y Int) (or (not (>= y x) (not (>= x 0)) (= (select a x) 1))))
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The bound (>= y x) is irrelevant and can be eliminated.
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This can be easily proved by using Fourier-Motzkin elimination.
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Limitations & Assumptions:
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- It assumes the input formula was already simplified.
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- It can only handle bounds in the diff-logic fragment.
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\remark This operation is subsumed by Fourier-Motzkin elimination.
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*/
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class elim_bounds_cfg : public default_rewriter_cfg {
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ast_manager & m;
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arith_util m_util;
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bool is_bound(expr * n, var * & lower, var * & upper);
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bool is_bound(expr * n);
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public:
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elim_bounds_cfg(ast_manager & m);
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bool reduce_quantifier(quantifier * old_q,
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expr * new_body,
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expr * const * new_patterns,
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expr * const * new_no_patterns,
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expr_ref & result,
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proof_ref & result_pr);
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};
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/**
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\brief Functor for applying elim_bounds2 in all
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universal quantifiers in an expression.
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Assumption: the formula was already skolemized.
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*/
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class elim_bounds_rw : public rewriter_tpl<elim_bounds_cfg> {
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protected:
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elim_bounds_cfg m_cfg;
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public:
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elim_bounds_rw(ast_manager & m):
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rewriter_tpl<elim_bounds_cfg>(m, m.proofs_enabled(), m_cfg),
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m_cfg(m)
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{}
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~elim_bounds_rw() override {}
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};
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#endif /* ELIM_BOUNDS2_H_ */
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