Questions tagged [model-checking]
Model checking refers to the following problem: given a model of a system, test automatically whether this model meets a given specification.
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Does this paper by Patrick Cousot describe an undecidable method for model checking?
All of the discussion is in the context of this paper.
I think that the whole procedure that the paper describes is not decidable, because if we can have an algorithm for it, then we can solve halting ...
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Real-life applications of pure Mealy machines
I'm currently studying formal methods in software engineering related to state machines, specifically Mealy machines. This made me wonder how relevant Mealy machines really are for practical ...
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Safety VS. Liveliness Property
I have to prove whether a certain property is safety or liveliness. The property represents the absence of deadlock so I expected it to be a safety property from what I read online.
The issue is that ...
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Transition System vs State Machines
Why there is no final state for a transition system? And why do NFA and DFA have final states? The transition system may or may not have any terminal states, but NFA/DFA has at least one final state (...
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How can I prove that LTL formula is valid?
I do not know with which technique i can prove if a LTL forumula is valid.
Let's say we have for example this one: ¬q U(¬p ∧ ¬q) → ¬Gp. How can prove if this valid or not? (should be true in any state ...
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First-order model checking is not fixed parameter tractable on general graphs
I read that the problem of first-order model checking is believed to be not fixed parameter tractable on general graphs.
Why is this the case? Would be happy about some reference
Thanks in advance!
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First-order model checking on general graphs is intractable
I read that the first-order model checking problem is intractable on general graphs.
How is this shown? Would be happy about some reference!
Thanks in advance
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Understanding a proof from a paper (model checking game)
I'm reading the paper: "Model Checking Games for Branching Time Logics" by Martin Lange and Colin Stirling - https://carrick.fmv.informatik.uni-kassel.de/~mlange/papers/jlc2000.pdf. The ...
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Abstract Interpretation: Connection between soundness relation and a Galois connection
I am currently studying the paper "Abstract Interpretation Frameworks" by Cousot and Cousot from 1992 (https://doi.org/10.1093/logcom/2.4.511) to gain an understanding of the theory behind ...
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Getting rid of "FG" in a LTL equation
i am currently struggling with a Linear temporal logic equation: $$\phi=FG( \lnot a\lor X \lnot a )$$
For my understanding, it means that starting at a certain point in the future, proposition a can ...
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Are automata useful in software verification?
I contrast the paradigm of SMT-based verification of software, such as in LiquidHaskell with the approach based on automata. To me it appears that automata are only used in the paradigm of model ...
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$Sat(EG^2\alpha)$ as a fixpoint of an operator
Currently I am studying CTL model checking. I found this exercise:
Consider the CTL formula $EG^2(\alpha)$ which means that there exists a path that satisfies $\alpha$ at every even position. Define $...
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Given LTL formulas $m$ and $p$, is there a tool that can check whether $m \models p$ does hold?
To the best of my understanding, $m \models p$ asks whether the LTL formula $p$ satisfies the LTL formula $m$. In other words, $m \to p$ is a tautology. Here are some examples of where $m \models p$ ...
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Does Rice's theorem apply to sequential logic circuits?
I am wondering if Rice's theorem (or something similar to that) applies also to sequential circuits. I.e. given any finite sequential circuit, can there be an algorithm that can formally verify any ...
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Check if given safety properties are regular, and if so construct NFAs
Let $\mathit{AP} = \{a, b, c\}$. Consider the following LT properties:
Between two neighboring occurrences of $a$, $b$ always holds.
Between two neighboring occurrences of $a$, $b$ occurs more often ...
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Automaton-based model checking on finite traces
I want to check whether a formula in finite LTL is valid on a finite, linear trace.
For infite traces I would create a Kripke structure of the trace and a Büchi automaton for the negated formula, ...
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Fault localisation using model checking
In many papers like Empirical Evaluation of the Tarantula Automatic Fault-Localization Technique there is a good explanation about how tarantula algorithm can be used with test suits. Is there any ...
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What are the limitations of symbolic model checking?
What are the limitations of the Symbolic Model Checking?
As far as I know, "state-space explosion" can still happen by this technique but it can explore much larger state space.
So, is the Symbolic ...
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Review of Formal Verification and How to Apply it to Greenfield Project [duplicate]
Last year I looked heavily into Formal Verification, such as automated theorem proving, model checking, type systems, symbolic evaluation, and many others. I probably spent a few weeks or maybe months ...
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What goes into proving two complicated programs are equivalent?
Say I wanted to prove that two programs were equivalent (either rigorously if possible, or informally if not). More specifically, say I have something relatively complex such as an HTTP server ...
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Proving that a property is k-inductive with an SMT solver (parametric resettable counter)
I'm following the slides at https://homepage.cs.uiowa.edu/~tinelli/talks/FT-11.pdf where Tinelli explains how k-induction works in the context of SMT based model checking.
A parametric and resettable ...
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Modeling a set of probabilistic concurrent processes
I'm looking into discrete-time Markov chains (DTMCs) for use in analyzing a probabilistic consensus protocol. One basic thing I haven't been able to figure out is how to model a set of independent ...
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Algorithm for computing $Pr[s \vDash C \bigcup^{\geq n} B]$ for probabilistic verification
I'm having some difficulty trying to come up with an algorithm for computing $Pr[s \vDash C ~\bigcup^{\geq n} B]$ given a finite Markov chain where $S$ is the set of states, $s \in S$, $B,C \subseteq ...
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Calculating probability of reaching state in DTMC
Consider a highly-connected graph of states & transitions where each transition is marked with a weight (representing probability of occurring) and the graph satisfies the Discrete Time Markov ...
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Safety property vs Liveness property
If i take a safety property $SP$ and a liveness property $LP$, is it true that the result of their intersection is a safety property (and not a liveness property) ? Why ?
Thanks
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Definition of liveness property in model checking
A property $P$ is simply a set of sequences of states and a certain program is characterized by its set of sequences of states, let's call it $T$. A program is compliant to a specific property P if $T\...
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Is model checking PSpace-hard *in formula size*?
Sistla/Clarke proved [SC82] that the LTL model-checking problem is PSpace-complete.
Sometimes people write that this problem is "PSpace-hard in $|\phi|$" (e.g. [LP85]). What does this mean formally?
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Are two CCS processes equivalent with respect to weak bisimilarity if and only if they satisfy exactly the same set of HML formulas?
I was skimming this recent paper and I was struck by the following statement:
two processes are equivalent with respect to weak bisimilarity if and only if they satisfy exactly the same set of HML ...
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Negation of the semantics of the Until operator in LTL
I have been looking at the Until operator and the release operator and when introduced to the release operator it was suggested that it is equivalent to:
$\phi R \psi \equiv \neg(\neg\phi U \neg \psi)...
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(Generally) How to specify asynchronous action with side effects using logic equations
Say you have this function call sequence:
function all() {
fn1()
fn2()
fn3()
}
And say that fn2 was asynchronous and ...
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Buchi automata in formal software verification
As I am studying the application of Buchi automata in formal software verification, I am interested in the computational complexity (or links to papers) for the algorithms used to solve the problem in ...
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Model Checking CTL* algorithm
Currently I'm trying to understand the CTL* model checking algorithm from this book. The basic idea is clear to that we can use the LTL algorithm to whenever we have a subformular $E\phi$ or $A\phi$ ...
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Validity of CTL formula $s_0 \models EG\ AF\ p$ in given model
I have been learning Verification by model checking recently and I get the following question:
Is the CTL formula $s_{0} \models EG\ AF\ p$ valid in the following model?
I think it is ...
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How to prove a LTL formula correct in a specific model?
I have been learning Verification by model checking recently and I get the following question:
$Whether\ the\ LTL\ formula\ M, q_3\ \models (X\ \lnot a) \rightarrow (F\ G\ \lnot a)\ is\ established\ ...
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How do you correctly write this sentence as a CTL formula?
Sentence: From every reachable state it is possible to reach a state where $p$ is true.
How do you write this sentence as a CTL formula? So far I only dealt with CTL syntax and trees but maybe it ...
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How to express the existence of winning strategy of the starter of a game in temporal logic?
Consider a two-player game. A winning strategy of a player is a strategy following which the player can always beat his opponent, no matter how his opponent responds.
A game can be unfolded to a ...
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How to collect all states of a behavior in TLA+?
Description of the problem:
I am modeling checking a distributed protocol against a global property with TLA+ developed by Leslie Lamport. The global property is defined on all states of a behavior (...
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How Model Checking works with User Interaction
In order to understand how to apply Model Checking, I am wondering how to apply it to a pseudo-realistic async program.
Say I have the following pseudocode:
...
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How to define the Atomic Propositions in Model Checking
The atomic propositions in Symbolic Model Checking form the state in the state-transition graph (the model $\mathcal{M}$ in Model Checking). The other part of Model Checking is the specification, ...
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What exactly state is in Model Checking
So I finally realized the difference between transition systems and automata, and now am closer to understanding Model Checking. One of the last pieces is understanding what exactly "state" is in ...
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Least fix point of CTL formula
In the book Logic in Computer Science on page 244, there is a proof that $[[E(\phi U\psi)]]$ is the least fixed point of $G(X)=[[\psi]] \cup ([[\phi]]\cap\mathop{\textrm{pre}}_\exists(X))$. I don't ...
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How does TLC check liveness properties?
The paper "Model Checking TLA+ Specifications" published in 1999 explained how TLC (Temporal Logic Checker) checks safety properties written in TLA+ developed by Lamport. At that time, TLC did not yet ...
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CTL satisfied by Kripke Structure
given a Kripke Structure I want to check if a CTL formula is satisfied or not.
the CTL is: $$ AG(c \vee AX\neg E((a\vee b)Uc)) $$
I have read that it is better to write to CTL in terms of $\wedge $ ...
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How to Construct Kripke Structure States from Nested Functions
Say I have these defined functions:
...
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Understanding a Single Step in the Model Checking Algorithm
This answer explains roughly how to convert a nested boolean function into a Binary Decision Diagram (BDD). This question is about how to structure the states for the BDD. Now in this question I am ...
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Equivalence preserving operator from CTL* to LTL
The question is about an operator that transforms any CTL* formula ${\psi}$ into a (not necessarily equivalent) LTL formula ${A\psi^d}$, where $d$ means syntactically removing all $A,E$ quantifiers ...
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How to prove a side effect in a function
I asked a question earlier about Saving to the Database, which was very general and about the requirements for a proof when you go through many layers of non-verified systems such as the network and ...
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What the State is, and Where it comes from, when Generating Reachability Graphs
For Timed Automata, I found Figure 1 below. For Coloured Petri Nets I found Figure 2. Both are for "Reachability Graph Construction".
However, they don't describe where they got the states from (...
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Acceptance conditions when translating LTL to Büchi automaton?
As an exercise in better understanding, I have been implementing the LTL to Generalized Büchi Automaton translation algorithm of Gerth, et al. (which is also discussed in Clarke, et al., Model ...
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Why do we have free variables in mu-calculus?
I'm reading the Model Chekcing book of E. M. Clarke and in the chapter about µ-calculus there is an example formula
$$
f = \mu Z. ((q \mathrel{\mathrm{AND}} Y) \mathrel{\mathrm{OR}} \langle a \rangle ...
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