* src/ltlvisit/contain.hh, src/ltlvisit/contain.cc (reduce_tau03):
New function, performing LTL reduction a la tauriainen.03.a83. * src/ltltest/equals.cc, src/ltltest/reduc.cc: Add support for the new reduction. * src/ltltest/reduc.test: Cut the test in half, and additionally test the new reduction. * src/ltltest/reduccmp.test: Run on the new reduction. * src/ltltest/Makefile.am: Adjust. * src/tgbatest/ltl2tgba.cc: Add new options to apply the reduction. * src/tgbatest/spotlbtt.test: Use them.
This commit is contained in:
Alexandre Duret-Lutz
parent
8cbec95253
commit
d4c9bf2b1e
10 changed files with 444 additions and 76 deletions
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@ -22,10 +22,16 @@
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#include "contain.hh"
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#include "destroy.hh"
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#include "clone.hh"
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#include "tunabbrev.hh"
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#include "ltlast/unop.hh"
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#include "ltlast/binop.hh"
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#include "ltlast/multop.hh"
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#include "ltlast/constant.hh"
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#include "tgba/tgbaproduct.hh"
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#include "tgbaalgos/gtec/gtec.hh"
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#include "tgbaalgos/save.hh"
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#include "tostring.hh"
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#include <iostream>
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namespace spot
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{
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namespace ltl
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@ -64,6 +70,32 @@ namespace spot
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return res;
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}
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// Check whether L(!l) is a subset of L(g).
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bool
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language_containment_checker::neg_contained(const formula* l,
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const formula* g)
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{
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const formula* nl = unop::instance(unop::Not, clone(l));
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const record_* rnl = register_formula_(nl);
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const formula* ng = unop::instance(unop::Not, clone(g));
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const record_* rng = register_formula_(ng);
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destroy(nl);
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destroy(ng);
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bool res = rnl->incompatible.find(rng) != rnl->incompatible.end();
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return res;
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}
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// Check whether L(l) is a subset of L(!g).
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bool
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language_containment_checker::contained_neg(const formula* l,
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const formula* g)
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{
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const record_* rl = register_formula_(l);
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const record_* rg = register_formula_(g);
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bool res = rl->incompatible.find(rg) != rl->incompatible.end();
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return res;
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}
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// Check whether L(l) = L(g).
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bool
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language_containment_checker::equal(const formula* l, const formula* g)
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@ -105,5 +137,217 @@ namespace spot
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}
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return &r;
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}
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namespace {
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struct reduce_tau03_visitor : public clone_visitor {
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bool stronger;
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language_containment_checker* lcc;
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reduce_tau03_visitor(bool stronger,
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language_containment_checker* lcc)
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: stronger(stronger), lcc(lcc)
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{
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}
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void
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visit(unop* uo)
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{
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formula* a = recurse(uo->child());
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switch (uo->op())
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{
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case unop::X:
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// if X(a) = a, then keep only a !
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if (stronger && lcc->equal(a, uo))
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{
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result_ = a;
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break;
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}
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default:
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result_ = unop::instance(uo->op(), a);
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}
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}
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void
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visit(binop* bo)
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{
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formula* a = recurse(bo->first());
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formula* b = recurse(bo->second());
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switch (bo->op())
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{
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case binop::U:
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// if (a U b) = b, then keep b !
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if (stronger && lcc->equal(bo, b))
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{
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destroy(a);
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result_ = b;
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}
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// if a => b, then a U b = b.
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else if ((!stronger) && lcc->contained(a, b))
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{
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destroy(a);
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result_ = b;
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}
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// if !a => b, then a U b = Fb
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else if (lcc->neg_contained(a, b))
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{
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destroy(a);
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result_ = unop::instance(unop::F, b);
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}
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else
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{
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result_ = binop::instance(binop::U, a, b);
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}
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break;
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case binop::R:
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// if (a R b) = b, then keep b !
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if (stronger && lcc->equal(bo, b))
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{
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destroy(a);
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result_ = b;
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}
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// if b => a, then a R b = b.
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else if ((!stronger) && lcc->contained(b, a))
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{
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destroy(a);
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result_ = b;
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}
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// if a => !b, then a R b = Gb
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else if (lcc->contained_neg(a, b))
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{
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destroy(a);
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result_ = unop::instance(unop::G, b);
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}
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else
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{
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result_ = binop::instance(binop::R, a, b);
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}
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break;
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default:
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result_ = binop::instance(bo->op(), a, b);
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}
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}
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void
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visit(multop* mo)
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{
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multop::vec* res = new multop::vec;
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unsigned mos = mo->size();
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for (unsigned i = 0; i < mos; ++i)
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res->push_back(recurse(mo->nth(i)));
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result_ = 0;
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bool changed = false;
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switch (mo->op())
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{
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case multop::Or:
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for (unsigned i = 0; i < mos; ++i)
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{
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if (!(*res)[i])
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continue;
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for (unsigned j = i + 1; j < mos; ++j)
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{
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if (!(*res)[j])
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continue;
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// if !i => j, then i|j = true
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if (lcc->neg_contained((*res)[i], (*res)[j]))
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{
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result_ = constant::true_instance();
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goto constant_;
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}
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// if i => j, then i|j = j
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else if (lcc->contained((*res)[i], (*res)[j]))
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{
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destroy((*res)[i]);
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(*res)[i] = 0;
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changed = true;
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break;
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}
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// if j => i, then i|j = i
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else if (lcc->contained((*res)[i], (*res)[j]))
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{
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destroy((*res)[j]);
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(*res)[j] = 0;
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changed = true;
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}
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}
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}
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break;
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case multop::And:
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for (unsigned i = 0; i < mos; ++i)
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{
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if (!(*res)[i])
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continue;
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for (unsigned j = i + 1; j < mos; ++j)
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{
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if (!(*res)[j])
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continue;
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// if i => !j, then i&j = false
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if (lcc->contained_neg((*res)[i], (*res)[j]))
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{
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result_ = constant::false_instance();
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goto constant_;
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}
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// if i => j, then i&j = i
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else if (lcc->contained((*res)[i], (*res)[j]))
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{
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destroy((*res)[j]);
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(*res)[j] = 0;
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changed = true;
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}
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// if j => i, then i&j = j
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else if (lcc->contained((*res)[i], (*res)[j]))
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{
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destroy((*res)[i]);
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(*res)[i] = 0;
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changed = true;
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break;
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}
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}
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}
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break;
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}
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if (changed)
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{
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multop::vec* nres = new multop::vec;
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for (unsigned i = 0; i < mos; ++i)
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if ((*res)[i])
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nres->push_back((*res)[i]);
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delete res;
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res = nres;
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}
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result_ = multop::instance(mo->op(), res);
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return;
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constant_:
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for (unsigned i = 0; i < mos; ++i)
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if ((*res)[i])
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destroy((*res)[i]);
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}
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formula*
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recurse(formula* f)
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{
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reduce_tau03_visitor v(stronger, lcc);
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const_cast<formula*>(f)->accept(v);
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return v.result();
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}
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};
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}
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formula*
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reduce_tau03(const formula* f, bool stronger)
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{
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bdd_dict b;
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reduce_tau03_visitor v(stronger,
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new language_containment_checker(&b,
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true, true,
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false, false));
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// reduce_tau03_visitor does not handle Xor, Implies, and Equiv.
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f = unabbreviate_ltl(f);
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const_cast<formula*>(f)->accept(v);
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destroy(f);
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delete v.lcc;
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return v.result();
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}
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}
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}
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@ -54,6 +54,10 @@ namespace spot
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/// Check whether L(l) is a subset of L(g).
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bool contained(const formula* l, const formula* g);
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/// Check whether L(!l) is a subset of L(g).
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bool neg_contained(const formula* l, const formula* g);
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/// Check whether L(l) is a subset of L(!g).
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bool contained_neg(const formula* l, const formula* g);
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/// Check whether L(l) = L(g).
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bool equal(const formula* l, const formula* g);
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@ -70,6 +74,32 @@ namespace spot
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/* Translation Maps */
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trans_map translated_;
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};
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/// \brief Reduce a formula using language containment relationships.
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///
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/// The method is taken from table 4.1 in
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/// \verbatim
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///@TechReport{ tauriainen.03.a83,
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/// author = {Heikki Tauriainen},
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/// title = {On Translating Linear Temporal Logic into Alternating and
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/// Nondeterministic Automata},
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/// institution = {Helsinki University of Technology, Laboratory for
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/// Theoretical Computer Science},
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/// address = {Espoo, Finland},
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/// month = dec,
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/// number = {A83},
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/// pages = {132},
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/// type = {Research Report},
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/// year = {2003},
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/// note = {Reprint of Licentiate's thesis}
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///}
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///
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/// (The "dagged" cells in the tables are not handled here.)
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///
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/// If \a stronger is set, additional rules are used to further
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/// reduce some U, R, and X usages.
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/// \endverbatim
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formula* reduce_tau03(const formula* f, bool stronger = false);
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}
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}
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