Partial Order Reductions
نویسنده
چکیده
Streszczenie Problem eksplozji stann ow mo_ ze zosta c ograniczony poprzez u_ zycie redukcji cz , e sciowo-porz , adkowych. Metody te polegaj , a na budowaniu tylko frag-mentu pee lnej przestrzeni stann ow programu, ktt ory jest wystarczaj , acy do wery-kacji formuu l logik temporalnych LTL ?X lub CTL ?X (tzn. LTL lub CTL* bez operatora nast , epnego kroku). Jest to zagwarantowane poprzez za-chowanie rr ownowa_ zno sci indukowanych przez te logiki pomi , edzy pee ln , a i zre-dukowan , a przestrzeni , a stann ow. Poniewa_ z rr ownowa_ zno s c indukowana przez CTL ?X jest du_ zo bardziej restryktywna ni_ z rr ownowa_ zno s c indukowana przez LTL ?X , powoduj , ac ograniczenie skali redukcji, rozwa_ zamy w tej pracy re-dukcje cz , es ciowo-porz , adkowe zachowuj , ace rr ownowa_ zno sci "pomi , edzy nimi", w szczegg olno sci rr ownowa_ zno s c indukowan , a przez uniwersalny fragment CTL ?X , nazywany ACTL ?X. Redukcje uzyskiwane stosuj , ac nasz , a metod , e zachowuj , a rr ownie_ z rozgaa l , ezion , a symulacj , e i ss lab , a symulacj , e, ale nie zawieraj , a si , e w redukc-jach otrzymywanych przez zastosowanie metody Peleda do weryykacji ww lasno sci logiki LTL ?X. Zatem, proponujemy te_ z ulepszenie metody redukcji dla LTL ?X. Abstract The "state explosion problem" can be alleviated by using partial order reduction techniques. These methods rely on expanding only a fragment of the full state space of a program, which is suucient for verifying the formulas of temporal logics LTL ?X or CTL ?X (i.e., LTL or CTL* without the next state operator). This is guaranteed by preserving either a stuttering maximal trace equivalence or a stuttering bisimulation between the full and the reduced state space. Since a stuttering bisimulation is much more restrictive than a stuttering maximal trace equivalence, resulting in less powerful reductions for CTL ?X , we study here partial order reductions that preserve equivalences "in-between", in particular a stuttering simulation which is induced by the universal fragment of CTL ?X , called ACTL ?X. The reductions generated by our method preserve also branching simulation and weak simulation, but surprisingly, they do not appear to be included into the reductions obtained by Peled's method for verifying LTL ?X properties. Therefore, …
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