1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
|
/********************* */
/*! \file term_formula_removal.h
** \verbatim
** Top contributors (to current version):
** Morgan Deters, Dejan Jovanovic, Tim King
** This file is part of the CVC4 project.
** Copyright (c) 2009-2017 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 Removal of term formulas
**
** Removal of term formulas.
**/
#include "cvc4_private.h"
#pragma once
#include <unordered_map>
#include <vector>
#include "context/cdinsert_hashmap.h"
#include "context/context.h"
#include "expr/node.h"
#include "smt/dump.h"
#include "util/bool.h"
#include "util/hash.h"
namespace CVC4 {
namespace theory {
class ContainsTermITEVisitor;
}/* CVC4::theory namespace */
typedef std::unordered_map<Node, unsigned, NodeHashFunction> IteSkolemMap;
class RemoveTermFormulas {
typedef context::CDInsertHashMap< std::pair<Node, int>, Node, PairHashFunction<Node, int, NodeHashFunction, BoolHashFunction> > ITECache;
ITECache d_iteCache;
static inline int cacheVal( bool inQuant, bool inTerm ) { return (inQuant ? 1 : 0) + 2*(inTerm ? 1 : 0); }
static bool hasNestedTermChildren( TNode node );
public:
RemoveTermFormulas(context::UserContext* u);
~RemoveTermFormulas();
/**
* By introducing skolem variables, this function removes all occurrences of:
* (1) term ITEs,
* (2) terms of type Boolean that are not Boolean term variables,
* (3) lambdas, and
* (4) Hilbert choice expressions.
* from assertions.
* All additional assertions are pushed into assertions. iteSkolemMap
* contains a map from introduced skolem variables to the index in
* assertions containing the new definition created in conjunction
* with that skolem variable.
*
* As an example of (1):
* f( (ite C 0 1)) = 2
* becomes
* f( k ) = 2 ^ ite( C, k=0, k=1 )
*
* As an example of (2):
* g( (and C1 C2) ) = 3
* becomes
* g( k ) = 3 ^ ( k <=> (and C1 C2) )
*
* As an example of (3):
* (lambda x. t[x]) = f
* becomes
* (forall x. k(x) = t[x]) ^ k = f
* where k is a fresh skolem function.
* This is sometimes called "lambda lifting"
*
* As an example of (4):
* (choice x. P( x ) ) = t
* becomes
* P( k ) ^ k = t
* where k is a fresh skolem constant.
*
* With reportDeps true, report reasoning dependences to the proof
* manager (for unsat cores).
*/
void run(std::vector<Node>& assertions, IteSkolemMap& iteSkolemMap, bool reportDeps = false);
/**
* Removes terms of the form (1), (2), (3) described above from node.
* All additional assertions are pushed into
* assertions. iteSkolemMap contains a map from introduced skolem
* variables to the index in assertions containing the new Boolean
* ite created in conjunction with that skolem variable.
*
* inQuant is whether we are processing node in the body of quantified formula
* inTerm is whether we are are processing node in a "term" position, that is, it is a subterm
* of a parent term that is not a Boolean connective.
*/
Node run(TNode node, std::vector<Node>& additionalAssertions,
IteSkolemMap& iteSkolemMap, bool inQuant, bool inTerm);
/**
* Substitute under node using pre-existing cache. Do not remove
* any ITEs not seen during previous runs.
*/
Node replace(TNode node, bool inQuant = false, bool inTerm = false) const;
/** Returns true if e contains a term ite. */
bool containsTermITE(TNode e) const;
/** Returns the collected size of the caches. */
size_t collectedCacheSizes() const;
/** Garbage collects non-context dependent data-structures. */
void garbageCollect();
/** Return the RemoveTermFormulas's containsVisitor. */
theory::ContainsTermITEVisitor* getContainsVisitor();
private:
theory::ContainsTermITEVisitor* d_containsVisitor;
};/* class RemoveTTE */
}/* CVC4 namespace */
|
