Head

GCC Code Coverage Report

Directory:	.		Exec	Total	Coverage
File:	src/theory/arith/arith_msum.cpp	Lines:	130	144	90.3 %
Date:	2021-09-30	Branches:	338	640	52.8 %


/******************************************************************************
 * Top contributors (to current version):
 *   Andrew Reynolds, Aina Niemetz
 *
 * 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.
 * ****************************************************************************
 *
 * Arithmetic utilities regarding monomial sums.
 */

#include "theory/arith/arith_msum.h"

#include "theory/rewriter.h"
#include "util/rational.h"

using namespace cvc5::kind;

namespace cvc5 {
namespace theory {

bool ArithMSum::getMonomial(Node n, Node& c, Node& v)
{
  if (n.getKind() == MULT && n.getNumChildren() == 2 && n[0].isConst())
  {
    c = n[0];
    v = n[1];
    return true;
  }
  return false;
}

bool ArithMSum::getMonomial(Node n, std::map<Node, Node>& msum)
{
  if (n.isConst())
  {
    if (msum.find(Node::null()) == msum.end())
    {
      msum[Node::null()] = n;
      return true;
    }
  }
  else if (n.getKind() == MULT && n.getNumChildren() == 2 && n[0].isConst())
  {
    if (msum.find(n[1]) == msum.end())
    {
      msum[n[1]] = n[0];
      return true;
    }
  }
  else
  {
    if (msum.find(n) == msum.end())
    {
      msum[n] = Node::null();
      return true;
    }
  }
  return false;
}

bool ArithMSum::getMonomialSum(Node n, std::map<Node, Node>& msum)
{
  if (n.getKind() == PLUS)
  {
    for (Node nc : n)
    {
      if (!getMonomial(nc, msum))
      {
        return false;
      }
    }
    return true;
  }
  return getMonomial(n, msum);
}

bool ArithMSum::getMonomialSumLit(Node lit, std::map<Node, Node>& msum)
{
  if (lit.getKind() == GEQ || lit.getKind() == EQUAL)
  {
    if (getMonomialSum(lit[0], msum))
    {
      if (lit[1].isConst() && lit[1].getConst<Rational>().isZero())
      {
        return true;
      }
      else
      {
        // subtract the other side
        std::map<Node, Node> msum2;
        NodeManager* nm = NodeManager::currentNM();
        if (getMonomialSum(lit[1], msum2))
        {
          for (std::map<Node, Node>::iterator it = msum2.begin();
               it != msum2.end();
               ++it)
          {
            std::map<Node, Node>::iterator it2 = msum.find(it->first);
            if (it2 != msum.end())
            {
              Node r = nm->mkNode(
                  MINUS,
                  it2->second.isNull() ? nm->mkConst(Rational(1)) : it2->second,
                  it->second.isNull() ? nm->mkConst(Rational(1)) : it->second);
              msum[it->first] = Rewriter::rewrite(r);
            }
            else
            {
              msum[it->first] = it->second.isNull() ? nm->mkConst(Rational(-1))
                                                    : negate(it->second);
            }
          }
          return true;
        }
      }
    }
  }
  return false;
}

Node ArithMSum::mkNode(const std::map<Node, Node>& msum)
{
  NodeManager* nm = NodeManager::currentNM();
  std::vector<Node> children;
  for (std::map<Node, Node>::const_iterator it = msum.begin(); it != msum.end();
       ++it)
  {
    Node m;
    if (!it->first.isNull())
    {
      m = mkCoeffTerm(it->second, it->first);
    }
    else
    {
      Assert(!it->second.isNull());
      m = it->second;
    }
    children.push_back(m);
  }
  return children.size() > 1
             ? nm->mkNode(PLUS, children)
             : (children.size() == 1 ? children[0] : nm->mkConst(Rational(0)));
}

int ArithMSum::isolate(
    Node v, const std::map<Node, Node>& msum, Node& veq_c, Node& val, Kind k)
{
  Assert(veq_c.isNull());
  std::map<Node, Node>::const_iterator itv = msum.find(v);
  if (itv != msum.end())
  {
    std::vector<Node> children;
    Rational r =
        itv->second.isNull() ? Rational(1) : itv->second.getConst<Rational>();
    if (r.sgn() != 0)
    {
      for (std::map<Node, Node>::const_iterator it = msum.begin();
           it != msum.end();
           ++it)
      {
        if (it->first != v)
        {
          Node m;
          if (!it->first.isNull())
          {
            m = mkCoeffTerm(it->second, it->first);
          }
          else
          {
            m = it->second;
          }
          children.push_back(m);
        }
      }
      val = children.size() > 1
                ? NodeManager::currentNM()->mkNode(PLUS, children)
                : (children.size() == 1
                       ? children[0]
                       : NodeManager::currentNM()->mkConst(Rational(0)));
      if (!r.isOne() && !r.isNegativeOne())
      {
        if (v.getType().isInteger())
        {
          veq_c = NodeManager::currentNM()->mkConst(r.abs());
        }
        else
        {
          val = NodeManager::currentNM()->mkNode(
              MULT,
              val,
              NodeManager::currentNM()->mkConst(Rational(1) / r.abs()));
        }
      }
      val = r.sgn() == 1 ? negate(val) : Rewriter::rewrite(val);
      return (r.sgn() == 1 || k == EQUAL) ? 1 : -1;
    }
  }
  return 0;
}

int ArithMSum::isolate(
    Node v, const std::map<Node, Node>& msum, Node& veq, Kind k, bool doCoeff)
{
  Node veq_c;
  Node val;
  // isolate v in the (in)equality
  int ires = isolate(v, msum, veq_c, val, k);
  if (ires != 0)
  {
    Node vc = v;
    if (!veq_c.isNull())
    {
      if (doCoeff)
      {
        vc = NodeManager::currentNM()->mkNode(MULT, veq_c, vc);
      }
      else
      {
        return 0;
      }
    }
    bool inOrder = ires == 1;
    veq = NodeManager::currentNM()->mkNode(
        k, inOrder ? vc : val, inOrder ? val : vc);
  }
  return ires;
}

Node ArithMSum::solveEqualityFor(Node lit, Node v)
{
  Assert(lit.getKind() == EQUAL);
  // first look directly at sides
  TypeNode tn = lit[0].getType();
  for (unsigned r = 0; r < 2; r++)
  {
    if (lit[r] == v)
    {
      return lit[1 - r];
    }
  }
  if (tn.isReal())
  {
    std::map<Node, Node> msum;
    if (ArithMSum::getMonomialSumLit(lit, msum))
    {
      Node val, veqc;
      if (ArithMSum::isolate(v, msum, veqc, val, EQUAL) != 0)
      {
        if (veqc.isNull())
        {
          // in this case, we have an integer equality with a coefficient
          // on the variable we solved for that could not be eliminated,
          // hence we fail.
          return val;
        }
      }
    }
  }
  return Node::null();
}

bool ArithMSum::decompose(Node n, Node v, Node& coeff, Node& rem)
{
  std::map<Node, Node> msum;
  if (getMonomialSum(n, msum))
  {
    std::map<Node, Node>::iterator it = msum.find(v);
    if (it == msum.end())
    {
      return false;
    }
    else
    {
      coeff = it->second;
      msum.erase(v);
      rem = mkNode(msum);
      return true;
    }
  }
  return false;
}

Node ArithMSum::negate(Node t)
{
  Node tt = NodeManager::currentNM()->mkNode(
      MULT, NodeManager::currentNM()->mkConst(Rational(-1)), t);
  tt = Rewriter::rewrite(tt);
  return tt;
}

Node ArithMSum::offset(Node t, int i)
{
  Node tt = NodeManager::currentNM()->mkNode(
      PLUS, NodeManager::currentNM()->mkConst(Rational(i)), t);
  tt = Rewriter::rewrite(tt);
  return tt;
}

void ArithMSum::debugPrintMonomialSum(std::map<Node, Node>& msum, const char* c)
{
  for (std::map<Node, Node>::iterator it = msum.begin(); it != msum.end(); ++it)
  {
    Trace(c) << "  ";
    if (!it->second.isNull())
    {
      Trace(c) << it->second;
      if (!it->first.isNull())
      {
        Trace(c) << " * ";
      }
    }
    if (!it->first.isNull())
    {
      Trace(c) << it->first;
    }
    Trace(c) << std::endl;
  }
  Trace(c) << std::endl;
}

}  // namespace theory
}  // namespace cvc5


Generated by: GCOVR (Version 3.2)

Line	Exec	Source
1		/******************************************************************************
2		* Top contributors (to current version):
3		* Andrew Reynolds, Aina Niemetz
4		*
5		* This file is part of the cvc5 project.
6		*
7		* Copyright (c) 2009-2021 by the authors listed in the file AUTHORS
8		* in the top-level source directory and their institutional affiliations.
9		* All rights reserved. See the file COPYING in the top-level source
10		* directory for licensing information.
11		* ****************************************************************************
12		*
13		* Arithmetic utilities regarding monomial sums.
14		*/
15
16		#include "theory/arith/arith_msum.h"
17
18		#include "theory/rewriter.h"
19		#include "util/rational.h"
20
21		using namespace cvc5::kind;
22
23		namespace cvc5 {
24		namespace theory {
25
26	325	bool ArithMSum::getMonomial(Node n, Node& c, Node& v)
27		{
28	325	if (n.getKind() == MULT && n.getNumChildren() == 2 && n[0].isConst())
29		{
30	325	c = n[0];
31	325	v = n[1];
32	325	return true;
33		}
34		return false;
35		}
36
37	396489	bool ArithMSum::getMonomial(Node n, std::map<Node, Node>& msum)
38		{
39	396489	if (n.isConst())
40		{
41	116734	if (msum.find(Node::null()) == msum.end())
42		{
43	116734	msum[Node::null()] = n;
44	116734	return true;
45		}
46		}
47	279755	else if (n.getKind() == MULT && n.getNumChildren() == 2 && n[0].isConst())
48		{
49	113113	if (msum.find(n[1]) == msum.end())
50		{
51	113113	msum[n[1]] = n[0];
52	113113	return true;
53		}
54		}
55		else
56		{
57	166642	if (msum.find(n) == msum.end())
58		{
59	166642	msum[n] = Node::null();
60	166642	return true;
61		}
62		}
63		return false;
64		}
65
66	249889	bool ArithMSum::getMonomialSum(Node n, std::map<Node, Node>& msum)
67		{
68	249889	if (n.getKind() == PLUS)
69		{
70	351086	for (Node nc : n)
71		{
72	248843	if (!getMonomial(nc, msum))
73		{
74		return false;
75		}
76		}
77	102243	return true;
78		}
79	147646	return getMonomial(n, msum);
80		}
81
82	101144	bool ArithMSum::getMonomialSumLit(Node lit, std::map<Node, Node>& msum)
83		{
84	101144	if (lit.getKind() == GEQ \|\| lit.getKind() == EQUAL)
85		{
86	83002	if (getMonomialSum(lit[0], msum))
87		{
88	83002	if (lit[1].isConst() && lit[1].getConst<Rational>().isZero())
89		{
90	15446	return true;
91		}
92		else
93		{
94		// subtract the other side
95	67556	std::map<Node, Node> msum2;
96	67556	NodeManager* nm = NodeManager::currentNM();
97	67556	if (getMonomialSum(lit[1], msum2))
98		{
99	157650	for (std::map<Node, Node>::iterator it = msum2.begin();
100	157650	it != msum2.end();
101		++it)
102		{
103	90094	std::map<Node, Node>::iterator it2 = msum.find(it->first);
104	90094	if (it2 != msum.end())
105		{
106		Node r = nm->mkNode(
107		MINUS,
108	30	it2->second.isNull() ? nm->mkConst(Rational(1)) : it2->second,
109	60	it->second.isNull() ? nm->mkConst(Rational(1)) : it->second);
110	15	msum[it->first] = Rewriter::rewrite(r);
111		}
112		else
113		{
114	142418	msum[it->first] = it->second.isNull() ? nm->mkConst(Rational(-1))
115	52339	: negate(it->second);
116		}
117		}
118	67556	return true;
119		}
120		}
121		}
122		}
123	18142	return false;
124		}
125
126	102	Node ArithMSum::mkNode(const std::map<Node, Node>& msum)
127		{
128	102	NodeManager* nm = NodeManager::currentNM();
129	204	std::vector<Node> children;
130	204	for (std::map<Node, Node>::const_iterator it = msum.begin(); it != msum.end();
131		++it)
132		{
133	204	Node m;
134	102	if (!it->first.isNull())
135		{
136	68	m = mkCoeffTerm(it->second, it->first);
137		}
138		else
139		{
140	34	Assert(!it->second.isNull());
141	34	m = it->second;
142		}
143	102	children.push_back(m);
144		}
145	102	return children.size() > 1
146		? nm->mkNode(PLUS, children)
147	204	: (children.size() == 1 ? children[0] : nm->mkConst(Rational(0)));
148		}
149
150	59725	int ArithMSum::isolate(
151		Node v, const std::map<Node, Node>& msum, Node& veq_c, Node& val, Kind k)
152		{
153	59725	Assert(veq_c.isNull());
154	59725	std::map<Node, Node>::const_iterator itv = msum.find(v);
155	59725	if (itv != msum.end())
156		{
157	57995	std::vector<Node> children;
158		Rational r =
159	57995	itv->second.isNull() ? Rational(1) : itv->second.getConst<Rational>();
160	57987	if (r.sgn() != 0)
161		{
162	208858	for (std::map<Node, Node>::const_iterator it = msum.begin();
163	208858	it != msum.end();
164		++it)
165		{
166	150879	if (it->first != v)
167		{
168	185800	Node m;
169	92900	if (!it->first.isNull())
170		{
171	63993	m = mkCoeffTerm(it->second, it->first);
172		}
173		else
174		{
175	28907	m = it->second;
176		}
177	92900	children.push_back(m);
178		}
179		}
180	115958	val = children.size() > 1
181	178032	? NodeManager::currentNM()->mkNode(PLUS, children)
182	31037	: (children.size() == 1
183	26299	? children[0]
184	62717	: NodeManager::currentNM()->mkConst(Rational(0)));
185	57979	if (!r.isOne() && !r.isNegativeOne())
186		{
187	1583	if (v.getType().isInteger())
188		{
189	924	veq_c = NodeManager::currentNM()->mkConst(r.abs());
190		}
191		else
192		{
193	1318	val = NodeManager::currentNM()->mkNode(
194		MULT,
195		val,
196	1318	NodeManager::currentNM()->mkConst(Rational(1) / r.abs()));
197		}
198		}
199	57979	val = r.sgn() == 1 ? negate(val) : Rewriter::rewrite(val);
200	57979	return (r.sgn() == 1 \|\| k == EQUAL) ? 1 : -1;
201		}
202		}
203	1746	return 0;
204		}
205
206	9157	int ArithMSum::isolate(
207		Node v, const std::map<Node, Node>& msum, Node& veq, Kind k, bool doCoeff)
208		{
209	18314	Node veq_c;
210	18314	Node val;
211		// isolate v in the (in)equality
212	9157	int ires = isolate(v, msum, veq_c, val, k);
213	9157	if (ires != 0)
214		{
215	18306	Node vc = v;
216	9155	if (!veq_c.isNull())
217		{
218	48	if (doCoeff)
219		{
220	44	vc = NodeManager::currentNM()->mkNode(MULT, veq_c, vc);
221		}
222		else
223		{
224	4	return 0;
225		}
226		}
227	9151	bool inOrder = ires == 1;
228	9151	veq = NodeManager::currentNM()->mkNode(
229		k, inOrder ? vc : val, inOrder ? val : vc);
230		}
231	9153	return ires;
232		}
233
234	22824	Node ArithMSum::solveEqualityFor(Node lit, Node v)
235		{
236	22824	Assert(lit.getKind() == EQUAL);
237		// first look directly at sides
238	45648	TypeNode tn = lit[0].getType();
239	36804	for (unsigned r = 0; r < 2; r++)
240		{
241	29814	if (lit[r] == v)
242		{
243	15834	return lit[1 - r];
244		}
245		}
246	6990	if (tn.isReal())
247		{
248	7028	std::map<Node, Node> msum;
249	6990	if (ArithMSum::getMonomialSumLit(lit, msum))
250		{
251	7028	Node val, veqc;
252	6990	if (ArithMSum::isolate(v, msum, veqc, val, EQUAL) != 0)
253		{
254	6990	if (veqc.isNull())
255		{
256		// in this case, we have an integer equality with a coefficient
257		// on the variable we solved for that could not be eliminated,
258		// hence we fail.
259	6952	return val;
260		}
261		}
262		}
263		}
264	38	return Node::null();
265		}
266
267		bool ArithMSum::decompose(Node n, Node v, Node& coeff, Node& rem)
268		{
269		std::map<Node, Node> msum;
270		if (getMonomialSum(n, msum))
271		{
272		std::map<Node, Node>::iterator it = msum.find(v);
273		if (it == msum.end())
274		{
275		return false;
276		}
277		else
278		{
279		coeff = it->second;
280		msum.erase(v);
281		rem = mkNode(msum);
282		return true;
283		}
284		}
285		return false;
286		}
287
288	88675	Node ArithMSum::negate(Node t)
289		{
290		Node tt = NodeManager::currentNM()->mkNode(
291	88675	MULT, NodeManager::currentNM()->mkConst(Rational(-1)), t);
292	88675	tt = Rewriter::rewrite(tt);
293	88675	return tt;
294		}
295
296	586	Node ArithMSum::offset(Node t, int i)
297		{
298		Node tt = NodeManager::currentNM()->mkNode(
299	586	PLUS, NodeManager::currentNM()->mkConst(Rational(i)), t);
300	586	tt = Rewriter::rewrite(tt);
301	586	return tt;
302		}
303
304	2277	void ArithMSum::debugPrintMonomialSum(std::map<Node, Node>& msum, const char* c)
305		{
306	7047	for (std::map<Node, Node>::iterator it = msum.begin(); it != msum.end(); ++it)
307		{
308	4770	Trace(c) << " ";
309	4770	if (!it->second.isNull())
310		{
311	2137	Trace(c) << it->second;
312	2137	if (!it->first.isNull())
313		{
314	1190	Trace(c) << " * ";
315		}
316		}
317	4770	if (!it->first.isNull())
318		{
319	3823	Trace(c) << it->first;
320		}
321	4770	Trace(c) << std::endl;
322		}
323	2277	Trace(c) << std::endl;
324	2277	}
325
326		} // namespace theory
327	22755	} // namespace cvc5