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Questions tagged [predicate-logic]

24 questions
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Combining Predicate Logic and BigO

I am a beginner to predicate logic and BigO and am having though time understanding the definition of BigO in terms of predicate logic in the picture attached. I particularly am unable to understand what is meant by n0 in this context. Any help is…
Dhruv
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Complexity of pattern matching for modus ponens logical conclusions

Is a Turing machine with added the following contant-time operation equivalent (in the sense that polynomial time remains polynomial time and exponential time remains exponential time) to a (usual) Turing machine: By predicates I will mean…
porton
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In predicate logic, is the "environment" only needed when free variables are present?

Suppose there exist no free variables in a given predicate logic formula. Is then a model alone sufficient to fully interpret the formula and make inferences? Don't we need an environment or variable lookup table (as often mentioned)?
apen
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Prolog: Deletion of all appearances of an element in a list

I am trying to create a predicate in Prolog which allows me to delete all occurrences of X in a list L. I have the following code: my_delete(X, L, R):- [] = L, [] = R my_delete(X, L, R):- [Y|K] = L, [Y|M] = R, my_delete(X, K, M), (Y \=…
Vladis Becker
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Computability: Proving a predicate is not recursively enumerable

Let P(p) <=> for each x, comp(p,x) is defined. Can anyone explain to me how to prove that P is not RE (recursively enumerable) ?
A. Othmane
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Hoare triple: Loop invariant and partial correctness

Below there is Hoare triple in which variable $a$ is an array of integers, $len$, $x, i$ are integer-valued variables, and $r$ is a Boolean-valued variable. I have to provide a loop invariant (using predicate logic) suitable for proving partial…
BoiD
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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: $\phi R \psi \equiv \neg(\neg\phi U \neg \psi)$ But when trying to get from the semantic…
Jack
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Discrete Mathematics Proofs for ∃ and ∀

Premises or Givens: $∃x(A(x) → B(x))$ $∀x (B(x) → K(x))$ To Prove: $∃x(A(x) → K(x))$ My Solution: $A(z) → B(z)$ From premise and Existential instantiation $x$ for $z$ $B(z) → K(z)$ From premise and Universal instantiation $x$ for…
Swaraj
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Proving a predicate assignment is correct

I am currently reading Formal Methods - An Appetizer and am stuck in chapter 3 (Program Verification). I am unfamiliar with logic and I do not think I understand the $\vDash$ notation correctly. I tried to work through Definition 3.8 by giving…
user148883
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Prove that any first-order logics with equality and a relation/functional symbol of arity more than 1 is undecidable

Definition: A formal logic system is decidable – if there is an algorithm that can determine if any given sentence is a theorem (or not). Based on this definition, I am not sure how to move to prove that, "any first-order logics with equality and a…
Avv
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First-order logic - Does there exist a sentence that is satisfiable by all infinite models and only by them?

Prove or Disprove: There is $\boldsymbol{no}$ alphabet $\Sigma$ and closed formula (no free variables) $\varphi$ above $\Sigma$, such that for any Model $M$ it holds that $M\models\varphi\iff\,|D^M|=\infty$. I'm not sure what is the classic way to…
Ella
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Show that exist a finite set of clauses F in first-order logic that Res*(F) is infinite

I'm kind of desperate at this point about this question. A predicate-logic resolution derivation of a clause $C$ from a set of clauses $F$ is a sequence of clauses $C_1,\dots,C_m$, with $C_m = C$ such that each $C_i$ is either a clause of $F$…
RnHdw
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Predicate Logics - double negation HELP me understand

Sorry for maybe a silly question but i need to understand how ¬(¬∀x ¬A(x)) equals ∀x ¬A(x) In my mind, the negation before the parenthesis will be applied to both ¬∀x and ¬A(x). So it would look like this: ¬(¬∀x ¬A(x)) = ¬¬∀x ¬¬A(x) A double…
logicsnewbie2019
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Natural deduction proof without any predicate

I am gaving trouble proving a natural deduction proof when there is no predicate given. Only conclusion is given. I understand the rules of elimnations, inclusions, IPs and others but I having trouble applying them when no predicate is given. The…
Arth Patel
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Must $x$ and $y$ be different in a statement of the form $\forall x \forall y \cdots$?

Given the following predicate formula $F$: $$\forall x \forall y [(\text{italian}(x) \Rightarrow (\text{winWC}(y) \Rightarrow \text{happy}(x))]$$ I am having trouble understanding whether $x$ and $y$ must be different elements. Also, I have been…
theantomc
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