Questions tagged [logic]
Questions related to mathematical logic and its use in computer science
745
questions
0
votes
0answers
17 views
Trouble with or statements and short circuiting [closed]
I've my code as follows:
class Main {
public static void main(String[] args) {
boolean s;
boolean x = true;
System.out.println(x || s);
}
}
I've learned that or statements in java ...
2
votes
0answers
66 views
Given undirected and connected graph G=(V,E). Prove for any DFS run: for any u,v∈V if u.d>v.d then u.d−v.d≥δ(u,v)
Given undirected and connected graph $G = (V,E)$.
Prove for any DFS run: for any $u,v \in V$ if $u.d>v.d$ then $u.d − v.d ≥ δ(u,v)$
$δ(u,v)$-distance of a shortest path (not necessarily unique) in ...
0
votes
0answers
10 views
Proving the existence of a $\Pi_1$-sentence in True Arithmetic that is independent of Peano Arithmetic
I am trying to wrap my head around how to prove the following statement:
There exists some $\Pi_1$-sentence $A$ such that $A \in \textbf{TA}$ but $\{A, \neg A\} \cap \textbf{PA} = \emptyset$.
$\...
-1
votes
0answers
12 views
Using a PDA, show that ( x * y ) + x is a valid string
Using a PDA, show that ( x * y ) + x is a valid string.
im having trouble with part C
1
vote
2answers
28 views
Are these two sensible and related or unrelated ways of regarding a logic system as a programming language?
When I am trying to understand logic programming languages e.g. Prolog, I am immediately confused by the following two ways of relating logic systems and programming languages or type systems.
In ...
4
votes
1answer
59 views
Is there a model of ZF¬C where some program always terminates but has no loop variant?
Wikipedia has a proof that every loop that terminates has a loop variant—a well-founded relation on the state space such that each iteration of the loop results in a state that is less than the ...
2
votes
0answers
22 views
How to prove following two statements are equivalent in Hilbert System?
statement 1: $Γ$ is satisfiable implies $Γ$ is consistent.
statement 2: If $Γ$ derives $α$ then $Γ$ entails $α$.
I can easily prove statement 1 from 2 , but not 2 from 1 (without using strong ...
1
vote
1answer
44 views
Meaning of $a\lor b \to b' \lor c'$
So I have done part a) but I have no clue what I am supposed to do for part b), I have been trying for days to wrap my head around and even asked my fellow course mates, none of which seem to know ...
1
vote
1answer
22 views
Simplification of a multi-index Boolean expression towards computation in fewer steps
Let $x_{ij} \in \{0,1\}$, $1 \leq i \leq M$ (typically, $M = 2000$), $1 \leq j \leq N$ (typically, $N = 10$), be Boolean variables. If possible at all, I would like to simplify the following ...
1
vote
1answer
44 views
General resolution in first order logic
Assuming you have a formula in first order logic like
$$(\forall_x p(x) \land \forall_x q(x)) \rightarrow \forall_x(p(x) \land q(x))$$
(which seems valid?)
Converting the formula to ...
3
votes
3answers
122 views
Are regular languages and their regular expressions part of computer science?
I am trying to understand if regular languages and their regular expressions are concepts of computer science in general and if these are discovered, or invented, by computer scientists, in particular....
0
votes
0answers
46 views
On the complexity of existential and universal quantifiers
I'm trying to analyze the time complexities of the two former kind of quantifiers, I need help figuring out if I'm following the right path or if I'm making mistakes, here's what I've produced so far:
...
4
votes
1answer
37 views
Is unification over regular expression equations doable?
By way of example, suppose I know that $X + a = b + Y$ where $X$ and $Y$ are variables standing for regular expressions, then $(X, Y) = (b, a)$ is a solution to this set of equations.
Generalizing ...
1
vote
1answer
20 views
What does it mean when a dot appears in a logic gate other than the NOT gate? (in logic diagrams)
For example, this gate:
looks like an OR gate, except there's a dot to the right. The dot is reminiscent of the fact that there's a dot in the NOT gate, so I wonder if it has something to do with ...
3
votes
1answer
39 views
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 ...
7
votes
2answers
2k views
Language to define perfectly a programming problem
Is there any language, which can be used to define all programming problems perfectly?
By perfectly, I mean with these two properties:
p is the problem.
d is the definition in the language.
P(d, p): ...
2
votes
1answer
38 views
Addition, multiplication, and apostrophe used to represent boolean algebra expressions?
I'm looking at a worksheet that expresses boolean logic expressions using multiplication, addition, and apostrophes; something I've never seen before.
I can make a guess that the apostrophe is ...
0
votes
0answers
14 views
How to compute (partial) consequence set for premises of the first order logic?
I am playing with the Sequent Calculus Trainer https://www.uni-kassel.de/eecs/fachgebiete/fmv/projects/sequent-calculus-trainer.html . It is game with judgments, where each judgment consists from: 1) ...
1
vote
1answer
62 views
Can a dfa return only the final state?
I am given an assignment to design a tiny arithmetic unit (from 0 to 15 inclusive) start with 0 and using a DFA. The operations are as follow:
increment x+1 and if x+1 is larger than 15 then x+1 ...
2
votes
0answers
19 views
Determining Cumulative Benefit of Orders with Various Items
I'm working on a project to change the location of items in a warehouse to allow me to ship items together which were bought in the purchase order (currently impossible due to conveyor logistics). The ...
0
votes
0answers
53 views
Why do intuitionists accept the nonconstructive proof that the halting problem is undecidable? [duplicate]
On the intuitionism page at Stanford Encyclopedia of Philosophy (SEP), it's said in Section 3.3 that
Because of the finiteness of a natural number in contrast to, for example, a real number, many ...
0
votes
2answers
38 views
Why there is forward chaining inference engine (reasoner) for description logics only and not for other logics?
Reasoner is forward chaining inference engine (https://en.wikipedia.org/wiki/Semantic_reasoner) as opposite to Prolog backward chaining SAT solver (for queries). Why there is reasoner for description ...
1
vote
1answer
31 views
Complexity of negation cancellation
Consider propositional logic over the connectives $\land$, $\lor$, and $\lnot$. Notation: $| \alpha |$ is the length of formula $\alpha$.
We are given a formula $\phi$. Cancel all cancellable ...
2
votes
2answers
30 views
How to show all false outputs in a circuit?
I have 3 input variables and the output for all 8 possible combinations is 0 (false). When making a circuit, how would I show this using gates or no gates at all? Thanks!
1
vote
1answer
52 views
Can someone explain the logic diagram for the Boolean expression NOT A OR B AND C
An IB question requests:
Construct the logic diagram for the Boolean expression NOT A OR B AND C.
The answer
looks to me like not A or (B and C), whereas what I expected only gets partial credit. ...
5
votes
2answers
186 views
checking '<' for two binary numbers in a cnf-formula
I want to check whether a arbitrary binary number is less or equal to another binary number in a cnf-formula. I can already construct a formula, which is not in cnf:
Lets say n and m are two-digit ...
0
votes
0answers
36 views
Did I prove the language is not regular?
I am trying to prove the following language that is not regular.
I used Pumping Lemma proof and my proof goes as follows:
Assume that L is regular and let p be the constant of Pumping-Lemma.
This ...
1
vote
0answers
10 views
Do forward chaining (Rete) business rules (Drools, ILOG) / production rules support higher order rules and compositionality?
There is this talk http://andrewcropper.com/pubs/jelia19-typed.pdf about higher order Prolog, about use of higher-order predicates (that takes other predicates as arguments) and compositionality of ...
3
votes
1answer
46 views
How to Implement a reversible OR operator with a Fredkin gate (controlled swap)?
How to implement a reversible OR operator with a Fredkin gate ?
0
votes
1answer
30 views
How to correctly negate a predicate bounded by some quantifiers?
this is a problem which was asked in GATE CS 2010.
This is question statement:
Q: Suppose the predicate F(x, y, t) is used to represent the statement that person x can fool person y at time t. which ...
0
votes
0answers
38 views
How to write negation of an 'AND' statement in logic
Suppose the given proposition is:
"Zach blocks emails and texts from Jennifer"
Where,
P implies "Zach blocks emails from Jennifer".
Q implies "Zach blocks texts from Jennifer".
So it's P AND Q in ...
0
votes
0answers
27 views
Are there lightweight logic of commonsense reasoning?
Logic generally is hard and probabilistic logic (with model counting, like ProbLog2) is even harder. But commonsense knowledge and reasoning is quite lightweight. There have been efforts to represent ...
3
votes
2answers
66 views
Euclidean Models
I am asked to prove that every Euclidean models satisfies $\diamond \diamond \diamond \varphi \to \diamond \diamond \varphi$. How can this be done? I don't see how it could even be true.
0
votes
2answers
40 views
prove that {$↔,⊕$} is incomplete set?
How do i prove that Is {$↔,⊕$} not a complete set ? I have no clue how to prove it .
3
votes
1answer
106 views
Are these 2 equivalent?
Is ∀x∀y∀z[φ(x,y)∧p(y,z)->p(x,z)] equivalent to ∀x∀y∀z[φ(x,y)∧p(x,z)->p(y,z)] ?
The only thing I can think of is that this question can be answered if we show that ...
0
votes
0answers
29 views
Mutually contradicting rules in Prolog
What will happen in a Prolog program, if I set two rules/facts which contradict each other..
will it go with the rule/fact that appears first.. or it will show an error?
4
votes
0answers
55 views
How shall I understand the definitions of `let` expression?
let as used in programming languages is defined in lambda calculus as per https://en.wikipedia.org/wiki/Let_expression#Let_definition_defined_from_lambda_calculus
...
0
votes
0answers
15 views
Observational Determinism using HyperPCTL
I've found no material on HyperPCTL, so if you know please help me.
This is the definition of Observational Determinism expressed using HyperPCTL and i have some questions.
$\forall \sigma \, \forall ...
0
votes
1answer
22 views
What can't guarded fragment of FO express?
I have some basic confusions about the definition of the guarded fragment of first-order logic. Hopefully someone can tell me where I'm wrong.
GF in FO is defined by:
Atomic formulas, $x=y$ and $R(...
2
votes
2answers
65 views
Is there a formal definition for iteration?
I wanted know if there is a formal definition of iteration. In the sense that, this definition will say that after the 4th iteration is termination or the 5th iteration and not the 2nd iteration. ...
0
votes
0answers
32 views
Using Hoare logic to show an invariant holds or using induction?
I want to know if given a while loop:
x = 0
while(x < 5){
x = x + 1
}
I want to show that x (at the a ith iteration of the loop), the value of i is ...
8
votes
1answer
462 views
Representation of the concatenation at the type level
I would like to learn more about concatenative programming through the creation of a small simple language, based on the stack and following the concatenative paradigm.
Unfortunately, I haven't found ...
1
vote
0answers
56 views
Datalog Program Equivalence with Fixed Universe Size
It is well known that to compute equivalence of two Datalog programs (or equivalently of two first order formulas with the least fixed point operator) wrt all possible inputs and universes, is ...
0
votes
1answer
72 views
Confusion about assignment axiom in Hoare logic
I wanted to know if we are given the f.f.g. Hoare triple:
{x = 43}x := x + 1{x = 44}
How do we show that this is a valid Hoare triple?
My attempt was:
Using the assignment axiom:
{x + 1 = 43} x := ...
0
votes
0answers
47 views
What are necessity and sufficiency?
I was reading deadlock topic from Operating Systems book by Stallings. It states four pre requisites for deadlock:
Mutual exclusion
No preemption
Hold and wait
Circular wait
It then have following ...
2
votes
0answers
127 views
Second Order QBF
Consider a universe with two elements 0,1 and a second order formula, i.e. of the form "forall R exists S ... such that F", where R,S are relation symbols of some given arity, and F is some first ...
1
vote
1answer
40 views
Substructural Prolog?
Substructural logic is logic without some or all of the structural rules. Is substructural Prolog, substructural logic programming possible? My question is connected with article https://link.springer....
2
votes
1answer
124 views
Create NOT gate from other gates
If we are given only one NOT gate and any number of OR and AND gates, then, can we simulate more NOT gates?
1
vote
2answers
91 views
Are $\mathsf{\#P}$ problems harder than $\mathsf{NP}$ problems
I have a method to solve the $\mathsf{\#P}$ version of 3SAT in a way that seemingly reduces it to an $\mathsf{NP}$ problem. - I don't have a formal understanding of these terms so I will just show an ...
1
vote
3answers
150 views
Can undecidability theorems be detected by a machine? [closed]
this question was originally written in mathoverflow, but a comment recommended me to rewrite it as a CS question.
This is not a mathematically formalized question. I'm sorry for that but think it's ...
