diff options
Diffstat (limited to 'src/theory/quantifiers/sygus/sygus_unif_io.cpp')
| -rw-r--r-- | src/theory/quantifiers/sygus/sygus_unif_io.cpp | 100 |
1 files changed, 73 insertions, 27 deletions
diff --git a/src/theory/quantifiers/sygus/sygus_unif_io.cpp b/src/theory/quantifiers/sygus/sygus_unif_io.cpp index c9db62735..207aa4c8e 100644 --- a/src/theory/quantifiers/sygus/sygus_unif_io.cpp +++ b/src/theory/quantifiers/sygus/sygus_unif_io.cpp @@ -2,9 +2,9 @@ /*! \file sygus_unif_io.cpp ** \verbatim ** Top contributors (to current version): - ** Andrew Reynolds, Haniel Barbosa + ** Andrew Reynolds, Haniel Barbosa, Aina Niemetz ** This file is part of the CVC4 project. - ** Copyright (c) 2009-2018 by the authors listed in the file AUTHORS + ** Copyright (c) 2009-2019 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 @@ -161,7 +161,12 @@ bool UnifContextIo::getStringIncrement(SygusUnifIo* sui, if (d_vals[j] == sui->d_true) { // example is active in this context - Assert(vals[j].isConst()); + if (!vals[j].isConst()) + { + // the value is unknown, thus we cannot use it to increment the strings + // position + return false; + } String mystr = vals[j].getConst<String>(); ival = mystr.size(); if (mystr.size() <= ex_vals[j].size()) @@ -199,7 +204,11 @@ bool UnifContextIo::isStringSolved(SygusUnifIo* sui, if (d_vals[j] == sui->d_true) { // example is active in this context - Assert(vals[j].isConst()); + if (!vals[j].isConst()) + { + // value is unknown, thus it does not solve + return false; + } String mystr = vals[j].getConst<String>(); if (ex_vals[j] != mystr) { @@ -448,12 +457,23 @@ void SubsumeTrie::getLeavesInternal(const std::vector<Node>& vals, ++it) { int new_status = status; - // if the current value is true + bool success = true; + // If the current value is true, then this is a relevant point. + // We must consider the value of this child. if (curr_val_true) { - if (status != 0) + if (it->first.isNull()) { - Assert(it->first.isConst() && it->first.getType().isBoolean()); + // The value of this child is unknown on this point, hence we + // do not recurse + success = false; + } + else if (status != 0) + { + // if the status is not zero (indicating that we have a mix of T/F), + // then we must compute the new status. + Assert(it->first.getType().isBoolean()); + Assert(it->first.isConst()); new_status = (it->first.getConst<bool>() ? 1 : -1); if (status != -2 && new_status != status) { @@ -461,7 +481,10 @@ void SubsumeTrie::getLeavesInternal(const std::vector<Node>& vals, } } } - it->second.getLeavesInternal(vals, pol, v, index + 1, new_status); + if (success) + { + it->second.getLeavesInternal(vals, pol, v, index + 1, new_status); + } } } } @@ -641,23 +664,41 @@ void SygusUnifIo::notifyEnumeration(Node e, Node v, std::vector<Node>& lemmas) for (unsigned j = 0, size = itsr->second.size(); j < size; j++) { Node res = itsr->second[j]; - Assert(res.isConst()); + // The value of this term for this example, or the truth value of + // the I/O pair if the role of this enumerator is enum_io. Node resb; if (eiv.getRole() == enum_io) { Node out = d_examples_out[j]; Assert(out.isConst()); - resb = res == out ? d_true : d_false; + // If the result is not constant, then we assume that it does + // not satisfy the example. This is a safe underapproximation + // of the good behavior of the current term, that is, we only + // produce solutions whose values are fully evaluatable on all input + // points. Notice that terms may be used as leaves of decision + // trees that are fully evaluatable on points in that branch, but + // are not evaluatable on others, e.g. (head x) in the solution: + // (ite ((_ is cons) x) (head x) 5) + resb = (res.isConst() && res == out) ? d_true : d_false; } else { - resb = res; + // We only set resb if it is constant, otherwise it remains null. + // This indicates its value cannot be determined. + if (res.isConst()) + { + resb = res; + } } cond_vals[resb] = true; results.push_back(resb); if (Trace.isOn("sygus-sui-enum")) { - if (resb.getType().isBoolean()) + if (resb.isNull()) + { + Trace("sygus-sui-enum") << "_"; + } + else if (resb.getType().isBoolean()) { Trace("sygus-sui-enum") << (resb == d_true ? "1" : "0"); } @@ -677,6 +718,7 @@ void SygusUnifIo::notifyEnumeration(Node e, Node v, std::vector<Node>& lemmas) std::vector<Node> subsume; if (cond_vals.find(d_false) == cond_vals.end()) { + Assert(cond_vals.size() == 1); // it is the entire solution, we are done Trace("sygus-sui-enum") << " ...success, full solution added to PBE pool : " @@ -917,23 +959,27 @@ bool SygusUnifIo::getExplanationForEnumeratorExclude( std::vector<unsigned> cmp_indices; for (unsigned i = 0, size = results.size(); i < size; i++) { - Assert(results[i].isConst()); - Assert(d_examples_out[i].isConst()); - Trace("sygus-sui-cterm-debug") - << " " << results[i] << " <> " << d_examples_out[i]; - Node cont = nm->mkNode(STRING_STRCTN, d_examples_out[i], results[i]); - Node contr = Rewriter::rewrite(cont); - if (contr == d_false) - { - cmp_indices.push_back(i); - Trace("sygus-sui-cterm-debug") << "...not contained." << std::endl; - } - else + // If the result is not constant, then it is worthless. It does not + // impact whether the term is excluded. + if (results[i].isConst()) { - Trace("sygus-sui-cterm-debug") << "...contained." << std::endl; - if (isConditional) + Assert(d_examples_out[i].isConst()); + Trace("sygus-sui-cterm-debug") + << " " << results[i] << " <> " << d_examples_out[i]; + Node cont = nm->mkNode(STRING_STRCTN, d_examples_out[i], results[i]); + Node contr = Rewriter::rewrite(cont); + if (contr == d_false) { - return false; + cmp_indices.push_back(i); + Trace("sygus-sui-cterm-debug") << "...not contained." << std::endl; + } + else + { + Trace("sygus-sui-cterm-debug") << "...contained." << std::endl; + if (isConditional) + { + return false; + } } } } |