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Questions tagged [computation-tree-logic]

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1answer
37 views

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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0answers
9 views

Timed Kripke structures with inequality constraints

I am having problems creating a timed Kripke structure $\mathcal{TK} = \langle S, \mathcal{T}, \rightarrow, L \rangle$ for a system that I have. My system, a timed automaton system (time base $\...
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How express this short sentence in CTL?

It's possible that in some following state you have that $x,y$ are both true simultaneously. I have taken a look on Wikipedia: https://en.wikipedia.org/wiki/Computation_tree_logic and if I ...
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1answer
27 views

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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1answer
29 views

Reduce the running by using doubly logarithmic tree

I have two algorithms $A$ and $B$ to solve a problem $P$ of size $n$. Algorithm $A$ takes $O(\log n)$ time on the PRAM using $O(n \log n)$ operations (done in parallel). Algorithm $B$ reduces the size ...
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2answers
74 views

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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1answer
162 views

Proving the equivalence of an LTL and a CTL formula

For a lecture I am attending, we have to prove that $$\forall \big(a \textsf{U} (b \land \forall \square a)\big) \equiv \big(a \textsf{U} (b \land \square a)\big).$$ That is, we need to prove that ...
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1answer
94 views

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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1answer
43 views

Linear Temporal Logic, Idempotent law

in many lecture notes, I have seen the LTL idempotent law for until and its equivalence is described as $\phi U(\phi U \psi) \equiv \phi U\psi$ and also $(\phi U \...
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1answer
64 views

LTL globally implies

I have got confused in undressing the informal definition of LTL below: $$G(\phi \Longrightarrow\psi)\Longrightarrow(G\phi \Longrightarrow G\psi)$$ in many literatures I have seen implies is said as ...
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0answers
23 views

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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0answers
39 views

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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1answer
57 views

Why is $AF \phi \lor \varphi$ not equivalent to $AF \phi \lor AF \varphi$?

Can someone explain to me (perhaps with an example) why $AF (\phi \lor \varphi)$ is not equivalent to $AF \phi \lor AF \varphi$. This seems counter-intuitive, because in any path where $\phi$ (or $\...
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1answer
375 views

Intuition behind straight-line programs

Wikipedia defines straight-line programs in the following manner: In mathematics, more specifically in computational algebra[disambiguation needed], a straight-line program (SLP) for a finite group ...
3
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1answer
80 views

CTL* query evaluation order

I'm currently trying to evaluate a CTL* expression and am not sure how to stepwisely evaluate the queries. For example I have EFG p. This means something like 'there is a path where eventually there ...
3
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1answer
228 views

What does “AF AX p” mean in CTL?

Both Logic in Computer Science (Huth and Ryan, 2004) and Branching vs. Linear Time: Final Showdown (Vardi, 2002), state something to this effect (paraphrased): In LTL, X F p and F X p are ...
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1answer
127 views

How to verify a property about a certain order of events in TCTL / UPPAAL?

I'd like to check if a certain order of events happens if another property holds true using UPPAAL and TCTL. ...
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1answer
107 views

An algorithm to compute a set of states that satisfy a specific CTL formula

Working through a past exam question and I'm unsure where to start or what form they want the answer in: Define an algorithm that receives as input a finite transition system TS defined over the set ...
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1answer
191 views

CTL - model checking for formula $A [a \cup b]$

I'm trying to verify if the following model satisfy $A [a \cup b]$: The algorithm I'm using is taken from "Concepts, Algorithms, and Tools for Model Checking", Joost-Pieter Katoen. In particular I ...
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1answer
603 views

CTL vs LTL - when a formula satisfy a model

I'm trying to understand the difference between LTL and CTL. In particular, i'm trying to understand when a model (a transition system eg. Kripke structure) satisfy a formula. This is my point of view:...
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1answer
119 views

Defining a new operator in CTL

Lets consider a new operator $B$ where $a B b$ means "in every execution, if $b$ holds some time, then $a$ does so before it" and we're asked to define it in CTL. My working: the system can only ...
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1answer
70 views

Defining a new (informal) operator in CTL

If you were given a "new operator" Wh and a formula a Wh b meaning that a holds for at least as long as b does (in all executions). How would you define this operator in CTL? This is an exercise ...
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2answers
343 views

Some slight confusion with the UNTIL operator in CTL (e.g. a U b)

I've sketched a very small transition system in paint that I'll use as an example. I want to see if $A(aUb)$ holds for this transition system. From my understanding, this CTL formula is asking if ...
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1answer
275 views

Difference between equivalence and implication

In terms of CTL formulae, what is the difference between equivalence and implication? (prop = some proposition, && = conjunction, AG = CTL syntax for "globally holds") E.g. AG (prop1 &&...
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1answer
150 views

Determining set of states that satisfy a CTL formulae

I'm trying to understand CTL formulae, and until now I've understood everything (or at least I thought I did). I have the following Kripke strucure: Now given the following CTL formulae ...
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1answer
413 views

Computation tree logic and Kripke structures

Specifications in Kripke structures are verified by Computation tree logic (CTL). However, refering to this Wikipedia article the CTL-operators are relative to a current state. So, when we want to ...
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1answer
355 views

Transition systems that satisfy LTL but not CTL, and vice versa

I am learning about temporal logic and model checking systems. One conceptual exercise that I am struggling with is how to create a transition system which satisfies only one of two given properties, ...
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0answers
78 views

Is there any open-source tools for verifying TCTL formulae over timed automata can be imported into my project?

In my project, there is one important step to automatically verify a timed automata with TCTL formulae. I briefly surveyed the tool UPPAAL that provides a GUI to construct a timed automata and to ...
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1answer
441 views

Techniques (tools) to convert temporal logic (CTL,CTL* or LTL) to μ-calculus formulae

Suppose one wants to use a μ-calculus model checker, but specify things in temporal logics, which is easier (more intuitive). Is there a technique (even better, a tool) that automatically translates ...
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3answers
2k views

Why use $\mu$-calculus and not LTL,CTL,CTL*?

It is known that the temporal logics LTL,CTL,CTL* can be translated/embedded into the $\mu$-calculus. In other words, the (modal) $\mu$-calculus subsumes these logics, (i.e. it is more expressive.) ...
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1answer
260 views

applying CTL/LTL model-checking on some system

I apologies if my title is vague, I'm trying to apply CTL/LTL model-checking on some system written in java, however, I still don't understand how to reach a result using either of the approaches ...
2
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1answer
145 views

Convert CTL* formula to CTL

I have a CTL* formula: $\mathsf{EF}[p\land \mathsf{AX}[q\ \mathsf{U}\ r]]$ but in my application, I am limited to CTL. To my understanding, this formula is no valid CTL and I wonder whether I can ...
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4answers
862 views

How can I decide manually whether two CTL formulae are equivalent?

Assume I have two formulae $\Phi$ and $\Psi$ (over the same set of atomic propositions $AP$) in CTL. We have that $\Phi \equiv \Psi$ iff $Sat_{TS}(\Phi) = Sat_{TS}(\Psi)$ for all transition systems $...