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
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
/******************************************************************************
* Top contributors (to current version):
* Haniel Barbosa, Andrew Reynolds, Gereon Kremer
*
* This file is part of the cvc5 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.
* ****************************************************************************
*
* The NlExtPurify preprocessing pass.
*
* Purifies non-linear terms.
*/
#include "preprocessing/passes/nl_ext_purify.h"
#include "expr/skolem_manager.h"
#include "preprocessing/assertion_pipeline.h"
#include "theory/rewriter.h"
namespace cvc5 {
namespace preprocessing {
namespace passes {
using namespace std;
using namespace cvc5::theory;
Node NlExtPurify::purifyNlTerms(TNode n,
NodeMap& cache,
NodeMap& bcache,
std::vector<Node>& var_eq,
bool beneathMult)
{
NodeManager* nm = NodeManager::currentNM();
SkolemManager* sm = nm->getSkolemManager();
if (beneathMult)
{
NodeMap::iterator find = bcache.find(n);
if (find != bcache.end())
{
return (*find).second;
}
}
else
{
NodeMap::iterator find = cache.find(n);
if (find != cache.end())
{
return (*find).second;
}
}
if (n.isClosure())
{
// don't traverse quantified formulas
return n;
}
Node ret = n;
if (n.getNumChildren() > 0)
{
if (beneathMult
&& (n.getKind() == kind::PLUS || n.getKind() == kind::MINUS))
{
// don't do it if it rewrites to a constant
Node nr = Rewriter::rewrite(n);
if (nr.isConst())
{
// return the rewritten constant
ret = nr;
}
else
{
// new variable
ret = sm->mkDummySkolem("__purifyNl_var",
n.getType(),
"Variable introduced in purifyNl pass");
Node np = purifyNlTerms(n, cache, bcache, var_eq, false);
var_eq.push_back(np.eqNode(ret));
Trace("nl-ext-purify") << "Purify : " << ret << " -> " << np
<< std::endl;
}
}
else
{
bool beneathMultNew = beneathMult || n.getKind() == kind::MULT;
bool childChanged = false;
std::vector<Node> children;
for (unsigned i = 0, size = n.getNumChildren(); i < size; ++i)
{
Node nc = purifyNlTerms(n[i], cache, bcache, var_eq, beneathMultNew);
childChanged = childChanged || nc != n[i];
children.push_back(nc);
}
if (childChanged)
{
ret = nm->mkNode(n.getKind(), children);
}
}
}
if (beneathMult)
{
bcache[n] = ret;
}
else
{
cache[n] = ret;
}
return ret;
}
NlExtPurify::NlExtPurify(PreprocessingPassContext* preprocContext)
: PreprocessingPass(preprocContext, "nl-ext-purify"){};
PreprocessingPassResult NlExtPurify::applyInternal(
AssertionPipeline* assertionsToPreprocess)
{
unordered_map<Node, Node, NodeHashFunction> cache;
unordered_map<Node, Node, NodeHashFunction> bcache;
std::vector<Node> var_eq;
unsigned size = assertionsToPreprocess->size();
for (unsigned i = 0; i < size; ++i)
{
Node a = (*assertionsToPreprocess)[i];
Node ap = purifyNlTerms(a, cache, bcache, var_eq);
if (a != ap)
{
assertionsToPreprocess->replace(i, ap);
Trace("nl-ext-purify")
<< "Purify : " << a << " -> " << (*assertionsToPreprocess)[i] << "\n";
}
}
if (!var_eq.empty())
{
unsigned lastIndex = size - 1;
Node veq = NodeManager::currentNM()->mkAnd(var_eq);
assertionsToPreprocess->conjoin(lastIndex, veq);
}
return PreprocessingPassResult::NO_CONFLICT;
}
} // namespace passes
} // namespace preprocessing
} // namespace cvc5
|
