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Pushdown automaton
About: Pushdown automaton is a research topic. Over the lifetime, 1868 publications have been published within this topic receiving 35399 citations.
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TL;DR: A new trust behavior model is built based on the observations' sequences, which are derived from the interactions with services, which is a deterministic PushDown Automaton (PDA) based Trust behavior model.
Abstract: We propose in this paper a model checking framework for service trust behaviors. We devise a new trust behavior model, which is a deterministic PushDown Automaton (PDA) based trust behavior model. This model is built based on the observations' sequences, which are derived from the interactions with services. Furthermore, we express the regular and non-regular trust behavior properties using Fixed point Logic with Chop (FLC). The model checking of service trust behaviors with respect to trust properties is performed using a symbolic FLC model checking algorithm. Finally, we present some experiments to assess the efficiency of the proposed algorithm.
19 citations
TL;DR: It is shown here that the sequences of level 2 are exactly the rational formal power series over one undeterminate.
Abstract: A sequence of natural numbers is said to have level k, for some natural integer k, if it can be computed by a deterministic pushdown automaton of level k (Fratani and Senizergues in Ann Pure Appl. Log. 141:363–411, 2006). We show here that the sequences of level 2 are exactly the rational formal power series over one undeterminate. More generally, we study mappings from words to words and show that the following classes coincide:
the mappings which are computable by deterministic pushdown automata of level 2
the mappings which are solution of a system of catenative recurrence equations
the mappings which are definable as a Lindenmayer system of type HDT0L.
We illustrate the usefulness of this characterization by proving three statements about formal power series, rational sets of homomorphisms and equations in words.
19 citations
01 Jun 2017
TL;DR: In this article, the authors characterize the complexity of liveness verification for parameterized systems consisting of a leader process and arbitrarily many anonymous and identical contributor processes, and show that the problem is decidable and has a surprisingly low complexity: it is NP-complete when all processes are finite-state machines, and is in NEXPTIME (and PSPACE-hard) when they are pushdown machines.
Abstract: We characterize the complexity of liveness verification for parameterized systems consisting of a leader process and arbitrarily many anonymous and identical contributor processes. Processes communicate through a shared, bounded-value register. While each operation on the register is atomic, there is no synchronization primitive to execute a sequence of operations atomically. We analyze the case in which processes are modeled by finite-state machines or pushdown machines and the property is given by a Buchi automaton over the alphabet of read and write actions of the leader. We show that the problem is decidable, and has a surprisingly low complexity: it is NP-complete when all processes are finite-state machines, and is in NEXPTIME (and PSPACE-hard) when they are pushdown machines. This complexity is lower than for the non-parameterized case: liveness verification of finitely many finite-state machines is PSPACE-complete, and undecidable for two pushdown machines. For finite-state machines, our proofs characterize infinite behaviors using existential abstraction and semilinear constraints. For pushdown machines, we show how contributor computations of high stack height can be simulated by computations of many contributors, each with low stack height. Together, our results characterize the complexity of verification for parameterized systems under the assumptions of anonymity and asynchrony.
19 citations
24 Jul 2000
TL;DR: A new efficient transformation algorithm with the time complexity O(n2) is introduced, which is a significant improvement from the previous algorithm.
Abstract: Cover automata were introduced in [1] as an efficient representation of finite languages. In [1], an algorithm was given to transform a DFA that accepts a finite language to a minimal deterministic finite cover automaton (DFCA) with the time complexity O(n4), where n is the number of states of the given DFA. In this paper, we introduce a new efficient transformation algorithm with the time complexity O(n2), which is a significant improvement from the previous algorithm.
19 citations
Journal Article•
TL;DR: It is shown that any sweeping automaton for the language (L$)* has to have at least √m/2 states whenever the nondeterministic message complexity of L is at least m, the first general method to establish lower bounds on the conciseness of sweeping automata.
Abstract: A deterministic sweeping automaton is a two-way deterministic automaton (2-DFA) which makes turns only at the left or right end of the input. We give a survey on recent lower bounds for the conciseness of sweeping automata. We also show that any sweeping automaton for the language (L$)* has to have at least √m/2 states whenever the nondeterministic message complexity of L is at least m. Thus we obtain the first general method to establish lower bounds on the conciseness of sweeping automata.
19 citations