scholarly journals Model checking usage policies

2014 ◽  
Vol 25 (3) ◽  
pp. 710-763 ◽  
Author(s):  
MASSIMO BARTOLETTI ◽  
PIERPAOLO DEGANO ◽  
GIAN LUIGI FERRARI ◽  
ROBERTO ZUNINO
Keyword(s):  
Model Checking ◽  
Polynomial Time ◽  
Real World ◽  
Formal Model ◽  
Expressive Power ◽  
Finite State Automata ◽  
Time Model ◽  
Real World Applications ◽  
Finite State ◽  
Resource Creation

We study usage automata, a formal model for specifying policies on the usage of resources. Usage automata extend finite state automata with some additional features, parameters and guards, that improve their expressivity. We show that usage automata are expressive enough to model policies of real-world applications. We discuss their expressive power, and we prove that the problem of telling whether a computation complies with a usage policy is decidable. The main contribution of this paper is a model checking technique for usage automata. The model is that of usages, i.e. basic processes that describe the possible patterns of resource access and creation. In spite of the model having infinite states, because of recursion and resource creation, we devise a polynomial-time model checking technique for deciding when a usage complies with a usage policy.

scholarly journals Copyful Streaming String Transducers

2021 ◽  
Vol 178 (1-2) ◽  
pp. 59-76
Author(s):  
Emmanuel Filiot ◽  
Pierre-Alain Reynier
Keyword(s):  
Polynomial Time ◽  
Equivalence Problem ◽  
Expressive Power ◽  
The Other ◽  
Finite State Automata ◽  
Finite State ◽  
Variable Content ◽  
Deterministic Automata ◽  
Intermediate Output ◽  
Linear Manner

Copyless streaming string transducers (copyless SST) have been introduced by R. Alur and P. Černý in 2010 as a one-way deterministic automata model to define transductions of finite strings. Copyless SST extend deterministic finite state automata with a set of variables in which to store intermediate output strings, and those variables can be combined and updated all along the run, in a linear manner, i.e., no variable content can be copied on transitions. It is known that copyless SST capture exactly the class of MSO-definable string-to-string transductions, and are as expressive as deterministic two-way transducers. They enjoy good algorithmic properties. Most notably, they have decidable equivalence problem (in PSpace). On the other hand, HDT0L systems have been introduced for a while, the most prominent result being the decidability of the equivalence problem. In this paper, we propose a semantics of HDT0L systems in terms of transductions, and use it to study the class of deterministic copyful SST. Our contributions are as follows: (i)HDT0L systems and total deterministic copyful SST have the same expressive power, (ii)the equivalence problem for deterministic copyful SST and the equivalence problem for HDT0L systems are inter-reducible, in quadratic time. As a consequence, equivalence of deterministic SST is decidable, (iii)the functionality of non-deterministic copyful SST is decidable, (iv)determining whether a non-deterministic copyful SST can be transformed into an equivalent non-deterministic copyless SST is decidable in polynomial time.

scholarly journals USING AN EXTENSIONS OF CTL* FOR SPECIFICATION AND VERIFICATION OF SEQUENTIAL REACTIVE SYSTEMS

2020 ◽  
Author(s):  
Anton Romanovich Gnatenko ◽  
◽  
Vladimir Anatolyevoch Zakharov ◽  
Keyword(s):  
Model Checking ◽  
Formal Model ◽  
Reactive Systems ◽  
Expressive Power ◽  
Binary Relations ◽  
Temporal Logics ◽  
Finite State Transducers ◽  
Control Signals ◽  
Data Control ◽  
Finite State

Sequential reactive systems such as controllers, device drivers, computer interpreters operate with two data streams and transform input streams of data (control signals, instructions) into output streams of control signals (instructions, data). Finite state transducers are widely used as an adequate formal model for information processing systems of this kind. Since runs of transducers develop over time, temporal logics, obviously, could be used as both simple and expressive formalism for specifying the behavior of sequential reactive systems. However, the conventional applied temporal logics (LTL, CTL) do not suit this purpose well, since their formulae are interpreted over omega-languages, whereas the behavior of transducers are represented by binary relations on infinite sequences, i.e. omega-transductions. To provide temporal logic with the ability to take into account this general feature of the behavior of reactive systems, we introduced new extensions of this logic. Two distinguished features characterize these extension: 1) temporal operators are parameterized by sets of streams (languages) admissible for input, and 2) sets (languages) of expected output streams are used as basic predicates. In the previous series of works we studied the expressive power and the model checking problem for Reg-LTL and Reg-CTL which are such extensions of LTL and CTL where the languages mentioned above are regular ones. We discovered that such an extension of temporal logics increases their expressive capability though retains the decidability of the model checking problem. Our next step in the systematic study of expressive and algorithmic properties of new extensions temporal logics is the analysis of the model checking problem for finite state transducers against Reg-CTL* formulae. In this paper we develop a model checking algorithm for Reg-CTL* and show that this problem is in ExpSpace.

Synthesis with Mandatory Stop Actions

2021 ◽  
Author(s):  
Giuseppe De Giacomo ◽  
Antonio Di Stasio ◽  
Giuseppe Perelli ◽  
Shufang Zhu
Keyword(s):  
Model Checking ◽  
Finite State Automata ◽  
Deep Impact ◽  
Synthesis Technique ◽  
Büchi Automata ◽  
Finite State ◽  
Ltl Synthesis ◽  
Buchi Automata ◽  
The Impact

We study the impact of the need for the agent to obligatorily instruct the action stop in her strategies. More specifically we consider synthesis (i.e., planning) for LTLf goals under LTL environment specifications in the case the agent must mandatorily stop at a certain point. We show that this obligation makes it impossible to exploit the liveness part of the LTL environment specifications to achieve her goal, effectively reducing the environment specifications to their safety part only. This has a deep impact on the efficiency of solving the synthesis, which can sidestep handling Buchi determinization associated to LTL synthesis, in favor of finite-state automata manipulation as in LTLf synthesis. Next, we add to the agent goal, expressed in LTLf, a safety goal, expressed in LTL. Safety goals must hold forever, even when the agent stops, since the environment can still continue its evolution. Hence the agent, before stopping, must ensure that her safety goal will be maintained even after she stops. To do synthesis in this case, we devise an effective approach that mixes a synthesis technique based on finite-state automata (as in the case of LTLf goals) and model-checking of nondeterministic Buchi automata. In this way, again, we sidestep Buchi automata determinization, hence getting a synthesis technique that is intrinsically simpler than standard LTL synthesis.

scholarly journals Fair Pairwise Exchange among Groups

2021 ◽  
Author(s):  
Zhaohong Sun ◽  
Taiki Todo ◽  
Toby Walsh
Keyword(s):  
Polynomial Time ◽  
Real World ◽  
Research Question ◽  
Polynomial Time Algorithm ◽  
Time Algorithm ◽  
Upper Bounds ◽  
Individual Rationality ◽  
Running Time ◽  
Graph Structures ◽  
Real World Applications

We study the pairwise organ exchange problem among groups motivated by real-world applications and consider two types of group formulations. Each group represents either a certain type of patient-donor pairs who are compatible with the same set of organs, or a set of patient-donor pairs who reside in the same region. We address a natural research question, which asks how to match a maximum number of pairwise compatible patient-donor pairs in a fair and individually rational way. We first propose a natural fairness concept that is applicable to both types of group formulations and design a polynomial-time algorithm that checks whether a matching exists that satisfies optimality, individual rationality, and fairness. We also present several running time upper bounds for computing such matchings for different graph structures.

scholarly journals A Transformation-Based Approach to Implication of GSTE Assertion Graphs

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Guowu Yang ◽  
William N. N. Hung ◽  
Xiaoyu Song ◽  
Wensheng Guo
Keyword(s):  
Model Checking ◽  
Directed Graphs ◽  
Classical Model ◽  
Regular Languages ◽  
Finite State Automaton ◽  
Finite State Automata ◽  
Symbolic Trajectory Evaluation ◽  
Finite State ◽  
Symbolic Trajectory ◽  
Language Containment

Generalized symbolic trajectory evaluation (GSTE) is a model checking approach and has successfully demonstrated its powerful capacity in formal verification of VLSI systems. GSTE is an extension of symbolic trajectory evaluation (STE) to the model checking ofω-regular properties. It is an alternative to classical model checking algorithms where properties are specified as finite-state automata. In GSTE, properties are specified as assertion graphs, which are labeled directed graphs where each edge is labeled with two labeling functions: antecedent and consequent. In this paper, we show the complement relation between GSTE assertion graphs and finite-state automata with the expressiveness of regular languages andω-regular languages. We present an algorithm that transforms a GSTE assertion graph to a finite-state automaton and vice versa. By applying this algorithm, we transform the problem of GSTE assertion graphs implication to the problem of automata language containment. We demonstrate our approach with its application to verification of an FIFO circuit.

AN AUTOMATA-BASED APPROACH TO CSCW VERIFICATION

2004 ◽  
Vol 13 (02) ◽  
pp. 183-209 ◽  
Author(s):  
CONSTANTINOS PAPADOPOULOS
Keyword(s):  
Model Checking ◽  
Software Development ◽  
Computer Supported Cooperative Work ◽  
Finite State Automata ◽  
Timing Constraints ◽  
Finite State ◽  
Concurrent Processes ◽  
State Models ◽  
Finite State Models ◽  
Insight Into

Software development for computer-supported cooperative work (CSCW) is a notoriously difficult task, involving often concurrent processes which are bound up with rigid timing constraints. To cope effectively with this difficulty, we propose in this paper the use of abstract finite-state models. The utility of these models is illustrated by encoding a CSCW system that we have built into finite-state automata, specifying in them a number of desired properties with temporal logic, and verifying these properties with model checking. By incorporating timing constraints into this process, we also gain insight into the usability of our system in real cooperative scenarios.

scholarly journals On the Model Checking Problem for Some Extension of CTL*

2020 ◽  
Vol 27 (4) ◽  
pp. 428-441
Author(s):  
Anton Romanovich Gnatenko ◽  
Vladimir Anatolyevich Zakharov
Keyword(s):  
Model Checking ◽  
Temporal Logic ◽  
Reactive Systems ◽  
Expressive Power ◽  
Binary Relations ◽  
Temporal Logics ◽  
Distinctive Features ◽  
Verification Problem ◽  
Finite State ◽  
Infinite Sequences

Sequential reactive systems include programs and devices that work with two streams of data and convert input streams of data into output streams. Such information processing systems include controllers, device drivers, computer interpreters. The result of the operation of such computing systems are infinite sequences of pairs of events of the request-response type, and, therefore, finite transducers are most often used as formal models for them. The behavior of transducers is represented by binary relations on infinite sequences, and so, traditional applied temporal logics (like HML, LTL, CTL, mu-calculus) are poorly suited as specification languages, since omega-languages, not binary relations on omega-words are used for interpretation of their formulae. To provide temporal logics with the ability to define properties of transformations that characterize the behavior ofreactive systems, we introduced new extensions ofthese logics, which have two distinctive features: 1) temporal operators are parameterized, and languages in the input alphabet oftransducers are used as parameters; 2) languages in the output alphabet oftransducers are used as basic predicates. Previously, we studied the expressive power ofnew extensions Reg-LTL and Reg-CTL ofthe well-known temporal logics oflinear and branching time LTL and CTL, in which it was allowed to use only regular languages for parameterization of temporal operators and basic predicates. We discovered that such a parameterization increases the expressive capabilities oftemporal logic, but preserves the decidability of the model checking problem. For the logics mentioned above, we have developed algorithms for the verification of finite transducers. At the next stage of our research on the new extensions of temporal logic designed for the specification and verification of sequential reactive systems, we studied the verification problem for these systems using the temporal logic Reg-CTL*, which is an extension ofthe Generalized Computational Tree Logics CTL*. In this paper we present an algorithm for checking the satisfiability of Reg-CTL* formulae on models of finite state transducers and show that this problem belongs to the complexity class ExpSpace.

scholarly journals The conjugacy problem for Higman’s group

2020 ◽  
Vol 30 (06) ◽  
pp. 1211-1235
Author(s):  
Owen Baker
Keyword(s):  
Fixed Points ◽  
Polynomial Time ◽  
Conjugacy Problem ◽  
Simple Groups ◽  
Finite State Automata ◽  
Dehn Function ◽  
Power Circuit ◽  
Finite State Transducers ◽  
Finite State ◽  
Circuit Technology

Higman’s group [Formula: see text] is a remarkable group with large (non-elementary) Dehn function. Higman constructed the group in 1951 to produce the first examples of infinite simple groups. Using finite state automata, and studying fixed points of certain finite state transducers, we show the conjugacy problem in [Formula: see text] is decidable for all inputs. Diekert, Laun and Ushakov have recently shown the word problem in [Formula: see text] is solvable in polynomial time, using the power circuit technology of Myasnikov, Ushakov and Won. Building on this work, we also show in a strongly generic setting that the conjugacy problem for [Formula: see text] has a polynomial time solution.

Eulerian Trails and Tours

2013 ◽  
pp. 81-95
Author(s):  
Mehdi Iranpoor ◽  
Davood Mohammaditabar
Keyword(s):  
Graph Theory ◽  
Polynomial Time ◽  
Real World ◽  
Simple Graphs ◽  
Polynomial Time Algorithms ◽  
Real World Applications ◽  
Euler Tours

When L. Euler used a representation of vertices and edges to explain a legend about the existence of a route that someone could cross each bridge of Konigsberg city exactly once and go back to the origin, he actually developed the graph theory. This new theory was found useful in explaining many problems. Then, theorems about the existence of such Euler tours that cross each edge of a graph exactly once were introduced. These theorems show that there should be some conditions for a graph to posses such a tour which in simple graphs is to be connected and even. Also, other definitions and applications of Euler tours in cases where the tour is not closed or the graph is directed were developed. Euler tours have many real world applications, and therefore, some polynomial time algorithms are developed to find such tours in graphs.

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