scholarly journals Model Check What You Can, Runtime Verify the Rest

10.29007/slnn ◽  
2018 ◽  
Author(s):  
Timothy L. Hinrichs ◽  
A. Prasad Sistla ◽  
Lenore D. Zuck
Keyword(s):  
Model Checking ◽  
Formal Verification ◽  
State Space ◽  
Model Check ◽  
Runtime Verification ◽  
Position Paper ◽  
Combine Model ◽  
Online Verification

Model checking and runtime verification are pillars of formal verification but for the most part are used independently. In this position paper we argue that the formal verification community would be well-served by developing theory, algorithms, implementations, and applications that combine model checking and runtime verification into a single, seamless technology. This technology would allow system developers to carefully choose the appropriate balance between offline verification of expressive properties (model checking) and online verification of important parts of the system's state space (runtime verification). We present several realistic examples where such technology appears necessary and a preliminary formalization of the idea.

On Improving Model Checking of Time Petri Nets and Its Application to the Formal Verification

2021 ◽  
Vol 12 (4) ◽  
pp. 68-84
Author(s):  
Naima Jbeli ◽  
Zohra Sbai
Keyword(s):  
Model Checking ◽  
Petri Nets ◽  
Formal Verification ◽  
State Space ◽  
Order Reduction ◽  
The State ◽  
Timing Constraints ◽  
Time Petri Nets ◽  
Explicit Timing ◽  
Class Graph

Time Petri nets (TPN) are successfully used in the specification and analysis of distributed systems that involve explicit timing constraints. Especially, model checking TPN is a hopeful method for the formal verification of such complex systems. For this, it is promising to lean to the construction of an optimized version of the state space. The well-known methods of state space abstraction are SCG (state class graph) and ZBG (graph based on zones). For ZBG, a symbolic state represents the real evaluations of the clocks of the TPN; it is thus possible to directly check quantitative time properties. However, this method suffers from the state space explosion. To attenuate this problem, the authors propose in this paper to combine the ZBG approach with the partial order reduction technique based on stubborn set, leading thus to the proposal of a new state space abstraction called reduced zone-based graph (RZBG). The authors show via case studies the efficiency of the RZBG which is implemented and integrated within the 〖TPN-TCTL〗_h^∆ model checking in the model checker Romeo.

scholarly journals Card-Based Cryptography Meets Formal Verification

2021 ◽  
Author(s):  
Alexander Koch ◽  
Michael Schrempp ◽  
Michael Kirsten
Keyword(s):  
Model Checking ◽  
Formal Verification ◽  
State Space ◽  
Lower Bounds ◽  
Bounded Model Checking ◽  
Minimal Length ◽  
State Spaces ◽  
Bounded State ◽  
Sat Solver ◽  
General Translation

AbstractCard-based cryptography provides simple and practicable protocols for performing secure multi-party computation with just a deck of cards. For the sake of simplicity, this is often done using cards with only two symbols, e.g., $$\clubsuit $$ ♣ and $$\heartsuit $$ ♡ . Within this paper, we also target the setting where all cards carry distinct symbols, catering for use-cases with commonly available standard decks and a weaker indistinguishability assumption. As of yet, the literature provides for only three protocols and no proofs for non-trivial lower bounds on the number of cards. As such complex proofs (handling very large combinatorial state spaces) tend to be involved and error-prone, we propose using formal verification for finding protocols and proving lower bounds. In this paper, we employ the technique of software bounded model checking (SBMC), which reduces the problem to a bounded state space, which is automatically searched exhaustively using a SAT solver as a backend. Our contribution is threefold: (a) we identify two protocols for converting between different bit encodings with overlapping bases, and then show them to be card-minimal. This completes the picture of tight lower bounds on the number of cards with respect to runtime behavior and shuffle properties of conversion protocols. For computing AND, we show that there is no protocol with finite runtime using four cards with distinguishable symbols and fixed output encoding, and give a four-card protocol with an expected finite runtime using only random cuts. (b) We provide a general translation of proofs for lower bounds to a bounded model checking framework for automatically finding card- and run-minimal (i.e., the protocol has a run of minimal length) protocols and to give additional confidence in lower bounds. We apply this to validate our method and, as an example, confirm our new AND protocol to have its shortest run for protocols using this number of cards. (c) We extend our method to also handle the case of decks on symbols $$\clubsuit $$ ♣ and $$\heartsuit $$ ♡ , where we show run-minimality for two AND protocols from the literature.

Schedulability Analysis for Timed Automata With Tasks

2021 ◽  
Vol 20 (5s) ◽  
pp. 1-26
Author(s):  
Jinghao Sun ◽  
Nan Guan ◽  
Rongxiao Shi ◽  
Guozhen Tan ◽  
Wang Yi
Keyword(s):  
Model Checking ◽  
State Space ◽  
Real Time ◽  
Timed Automata ◽  
Schedulability Analysis ◽  
Scheduling Theory ◽  
Real Time Scheduling ◽  
Analysis Techniques ◽  
Model Complex ◽  
Time Scheduling

Research on modeling and analysis of real-time computing systems has been done in two areas, model checking and real-time scheduling theory. In model checking, an expressive modeling formalism such as timed automata (TA) is used to model complex systems, but the analysis is typically very expensive due to state-space explosion. In real-time scheduling theory, the analysis techniques are highly efficient, but the models are often restrictive. In this paper, we aim to exploit the possibility of applying efficient analysis techniques rooted in real-time scheduling theory to analysis of real-time task systems modeled by timed automata with tasks (TAT). More specifically, we develop efficient techniques to analyze the feasibility of TAT-based task models (i.e., whether all tasks can meet their deadlines on single-processor) using demand bound functions (DBF), a widely used workload abstraction in real-time scheduling theory. Our proposed analysis method has a pseudo-polynomial time complexity if the number of clocks used to model each task is bounded by a constant, which is much lower than the exponential complexity of the traditional model-checking based analysis approach (also assuming the number of clocks is bounded by a constant). We apply dynamic programming techniques to implement the DBF-based analysis framework, and propose state space pruning techniques to accelerate the analysis process. Experimental results show that our DBF-based method can analyze a TAT system with 50 tasks within a few minutes, which significantly outperforms the state-of-the-art TAT-based schedulability analysis tool TIMES.

A Methodology for Automatic Formal Verification of Enterprise Architecture

2019 ◽  
Vol 10 (1) ◽  
pp. 1-19
Author(s):  
Eduard Babkin ◽  
Pavel Malyzhenkov ◽  
Marina Ivanova ◽  
Nikita Ponomarev
Keyword(s):  
Model Checking ◽  
Formal Verification ◽  
Iterative Process ◽  
Enterprise Architecture ◽  
Description Language ◽  
Architecture Description Language ◽  
Business Modeling ◽  
Business Alignment ◽  
Architecture Description ◽  
Software Prototype

For over a decade, IT-business alignment has been ranked as a top-priority management concern, but there is little research on practical ways to achieve the alignment. EA development is a continuous iterative process, which implicitly ensures the achievement of a specific IT-business alignment level. Therefore, it is necessary to formalize the requirements for architecture and be able to automatically verify them. The authors propose a new methodology for detecting logical contradictions in enterprise architecture models based on a model checking approach adopted in the context of business modeling. In such a methodology, they use ArchiMate standard for a conceptual enterprise architecture description language which is fully aligned with TOGAF. The authors also offer several important verification queries and demonstrate practical applicability of their approach using a software prototype of the modeling tool which exploits MIT Alloy Analyzer model checking framework integrated with AchiMate Archi workbench.

A Generic Approach on How to Formally Specify and Model Check Path Finding Algorithms: Dijkstra, A* and LPA*

2020 ◽  
Vol 30 (10) ◽  
pp. 1481-1523
Author(s):  
Kazuhiro Ogata
Keyword(s):  
Model Checking ◽  
Shortest Path ◽  
Formal Specification ◽  
Model Check ◽  
Shortest Paths ◽  
Path Finding ◽  
Property A ◽  
Goal Node ◽  
The Cost ◽  
Start Node

The paper describes how to formally specify three path finding algorithms in Maude, a rewriting logic-based programming/specification language, and how to model check if they enjoy desired properties with the Maude LTL model checker. The three algorithms are Dijkstra Shortest Path Finding Algorithm (DA), A* Algorithm and LPA* Algorithm. One desired property is that the algorithms always find the shortest path. To this end, we use a path finding algorithm (BFS) based on breadth-first search. BFS finds all paths from a start node to a goal node and the set of all shortest paths is extracted. We check if the path found by each algorithm is included in the set of all shortest paths for the property. A* is an extension of DA in that for each node [Formula: see text] an estimation [Formula: see text] of the distance to the goal node from [Formula: see text] is used and LPA* is an incremental version of A*. It is known that if [Formula: see text] is admissible, A* always finds the shortest path. We have found a possible relaxed sufficient condition. The relaxed condition is that there exists the shortest path such that for each node [Formula: see text] except for the start node on the path [Formula: see text] plus the cost to [Formula: see text] from the start node is less than the cost of any non-shortest path to the goal from the start. We informally justify the relaxed condition. For LPA*, if the relaxed condition holds in each updated version of a graph concerned including the initial graph, the shortest path is constructed. Based on the three case studies for DA, A* and LPA*, we summarize the formal specification and model checking techniques used as a generic approach to formal specification and model checking of path finding algorithms.

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