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Generalize computation of is.eventual and is.universal.

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* src/ltlast/binop.cc (binop::binop): Generalize detection
of pure eventualities and purely universal formulae.  E.g.
`f U g' is a pure eventuality if g is a pure eventuality
(regardless of f) or if g is 1.
* src/ltlast/unop.cc (unop::unop): Compute is.eventual
and is.universal for Not.
* src/ltltest/kind.test: Adjust.
This commit is contained in:
Alexandre Duret-Lutz 2011-05-23 15:06:57 +02:00
parent 9f7ef5d0c3
commit 8ecf57e832
3 changed files with 29 additions and 18 deletions
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43
src/ltlast/binop.cc
View file

@ -37,23 +37,30 @@ namespace spot
binop::binop(type op, formula* first, formula* second)
: ref_formula(BinOp), op_(op), first_(first), second_(second)
{
// Beware: (f U g) is purely eventual if both operands
// are purely eventual, unlike in the proceedings of
// Beware: (f U g) is a pure eventuality if both operands
// are pure eventualities, unlike in the proceedings of
// Concur'00. (The revision of the paper available at
// http://www.bell-labs.com/project/TMP/ is fixed.) See
// also http://arxiv.org/abs/1011.4214 for a discussion
// also http://arxiv.org/abs/1011.4214v2 for a discussion
// about this problem. (Which we fixed in 2005 thanks
// to LBTT.)
// This means that we can use the following line to handle
// all cases of (f U g), (f R g), (f W g), (f M g) for
// universality and eventuality.
props = first->get_props() & second->get_props();
// The matter can be further refined because:
// (f U g) and (g M f) are pure eventualities if
// g is a pure eventuality (regardless of f)
// or f == 1
// (f W g) and (g R f) are purely universal if
// f is purely universal (regardless of g)
// or g == 0
switch (op)
{
case Xor:
case Equiv:
is.eventual = false;
is.universal = false;
is.sere_formula = is.boolean;
is.sugar_free_boolean = false;
is.in_nenoform = false;
@ -78,6 +85,8 @@ namespace spot
}
break;
case Implies:
is.eventual = false;
is.universal = false;
is.sere_formula = is.boolean;
is.sugar_free_boolean = false;
is.in_nenoform = false;
@ -148,9 +157,9 @@ namespace spot
assert(second->is_psl_formula());
break;
case U:
// 1 U a = Fa
if (first == constant::true_instance())
is.eventual = 1;
// f U g is universal if g is eventual, or if f == 1.
is.eventual = second->is_eventual();
is.eventual |= (first == constant::true_instance());
is.boolean = false;
is.eltl_formula = false;
is.sere_formula = false;
@ -168,9 +177,9 @@ namespace spot
// is.syntactic_persistence = Persistence U Persistance
break;
case W:
// a W 0 = Ga
if (second == constant::false_instance())
is.universal = 1;
// f W g is universal if f is universal, or if g == 0.
is.universal = first->is_universal();
is.universal |= (second == constant::false_instance());
is.boolean = false;
is.eltl_formula = false;
is.sere_formula = false;
@ -188,9 +197,9 @@ namespace spot
break;
case R:
// 0 R a = Ga
if (first == constant::false_instance())
is.universal = 1;
// g R f is universal if f is universal, or if g == 0.
is.universal = second->is_universal();
is.universal |= (first == constant::false_instance());
is.boolean = false;
is.eltl_formula = false;
is.sere_formula = false;
@ -208,9 +217,9 @@ namespace spot
break;
case M:
// a M 1 = Fa
if (second == constant::true_instance())
is.eventual = 1;
// g M f is universal if g is eventual, or if f == 1.
is.eventual = first->is_eventual();
is.eventual |= (second == constant::true_instance());
is.boolean = false;
is.eltl_formula = false;
is.sere_formula = false;

2
src/ltlast/unop.cc
View file

@ -39,6 +39,8 @@ namespace spot
switch (op)
{
case Not:
is.eventual = child->is_universal();
is.universal = child->is_eventual();
is.in_nenoform = (child->kind() == AtomicProp);
is.sere_formula = is.boolean;

2
src/ltltest/kind.test
View file

@ -40,7 +40,7 @@ check '!(a|b)' 'B&xfLEPSFsgopr'
check 'F(a)' '&!xLPegopr'
check 'G(a)' '&!xLPusopr'
check 'a U b' '&!xfLPgopr'
check 'a U Fb' '&!xLPgopr'
check 'a U Fb' '&!xLPegopr'
check 'Ga U b' '&!xLPopr'
check '1 U a' '&!xfLPegopr'
check 'a W b' '&!xfLPsopr'