I am testing how similar are "assignment"-like models and "Skolem-function"-like models in Z3. Thus, I proposed an experiment: I will create a formul ...

A Skolem model in Z3 should be unique, but is printing several (and repeated)

I am testing how similar are "assignment"-like models and "Skolem-function"-like models in Z3. Thus, I proposed an experiment: I will create a formul ...

"Intersection" of two Skolem functions is not as expected in Z3(Py)

Z3(Py) does not “intersect” Skolem functions as I expected. I will try to explain my doubt using an imaginary problem which is the one that I have be ...

A model of a simple formula 'Exists([y],ForAll([x],Phi))' should be 'y=2' but Z3 it is returning '[]'

Note the following Z3-Py code: This prints: My question is: why is the model empty? I mean, I think y=2 should be a model... Note that the same ...

What does a model mean in a universally quantified formula? Is it a function?

Consider these two formulae: Exists y. Forall x. (y>x), which is unsat. Forall x. Exists y. (y>x), which is sat. Note that we cannot fi ...

In Z3, I cannot understand result of quantifier elimination of Exists y. Forall x. (x>=2) => ((y>1) /\ (y<=x))

In Z3-Py, I am performing quantifier elimination (QE) over the following formulae: Exists y. Forall x. (x>=2) => ((y>1) /\ (y<=x)) F ...

Lean prover: prove existential quantifier by providing an example

I am a beginner in lean prover and I have struggled a bit with the following example: I need to proof the following ∃ x, f x Where f is a func ...

What is the use of max m in the lazy quantifiers {n,m}??

In regex, we have greedy and lazy quantifiers. The greedy quantifier {n,m} matches the preceding atom/character/group a minimum of n and a maximum of ...

Z3 cannot check equivalence of two formulae

(Why are not the math formulae showing correctly?) I am performing a test over the Z3 library in Python (Collab) to see whether it knows to distingui ...

Understanding quantifiers in z3

I'm trying to understand this example: solve([y == x + 1, ForAll([y], Implies(y <= 0, x < y))]) but after reading the explanation I still don' ...

Dafny as a SAT-QBF solver is not giving right results

I am trying to get the habit to use Dafny as a friendly SAT-QBF solver for some simple formulae, since doing it in, for instance, Z3 is too uncomforta ...

Dafny invalid Ident

I am getting an invalid Ident error in the forall line (from is to the first i), does anybody know why? This is unusual. Version 3.0.0. ...

TypeError: unsupported operand type(s) for /: 'str' and 'int' for

I am using python 3.7 My list data looks like this My code For parsing the file Printing to a csv file uses I am getting this error: TypeE ...

Type variable introduction for existential types

Is there any binder in haskell to introduce a type variable (and constraints) quantified in a type ? I can add an extra argument, but it defeats the ...

Complex quantifiers in Idris?

Now I know, it's possible to express quantifiers via dependent types. So I wrote a simple realization for this "for all (a, b: N): exists (c: N): c = ...

How is the scope of a nested universal quantifier determined (higher-rank types)?

Originally I assumed the scope of a nested universal quantifier on the LHS of a function type can be determined purely syntactical, i.e. everything in ...

Why do I get different backtracking with these Raku regexes?

I'm getting unexpected backtracking of the + quantifier of a Raku regex. In this regex: I get the expected result: That is, the (greedy) + quan ...

Regex capture group with different quantifiers

The text I am parsing includes asterisks before and after the capture group, as well as within the capture group. The pattern I have identified to par ...

solving quantifier-free VC using z3

I was reading this research paper: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.365.9467&rep=rep1&type=pdf So, in summary, they a ...

regex quantifiers in bash --simple vs extended matching {n} times

I'm using the bash shell and trying to list files in a directory whose names match regex patterns. Some of these patterns work, while others don't. Fo ...

z3 with quantifiers and arrays, along with corresponding C code for Seahorn

The below program returns unsat when ran on z3. I don't get, what does the line "forall" actually mean; Does it mean, for all arrays - Int y [Int], ...

Sorted:

Quality: