Webpage for Mathematical Logic

Important Question Types:

  1. Checking validity of First Order Logic Statements
  2. Checking validity of Propositional Logic

Recent questions tagged mathematical-logic

53 53 votes
8 8 answers
15.8k
15.8k views
​​​Let $P(x)$ be an arbitrary predicate over the domain of natural numbers. Which ONE of the following statements is TRUE?$\big (P(0) \wedge \big( \forall x [P(x) \Righta...
17 17 votes
4 4 answers
13.0k
13.0k views
​​​​​​If $P \: e^{x} = Q \: e^{-x}$ for all real values of $x$, which one of the following statements is true?$P = Q = 0$$P = Q = 1$$P = 1; Q = -1$$\frac{P}{Q} = 0$ 
35 35 votes
6 6 answers
9.0k
9.0k views
Which of the following predicate logic formulae/formula is/are CORRECT representation(s) of the statement: "Everyone has exactly one mother"?The meanings of the predicate...
5 5 votes
1 1 answer
482
482 views
Select the statement that is the negation of "Some weasels are cuddly."No weasels are cuddly.All weasels are cuddly.Some weasels are not cuddly.All cuttlefish are weasely...
2 2 votes
1 1 answer
320
320 views
We use the dictionary:\begin{array}{ll}M & \text{domain of men} \\s & \text{Sharon} \\N(x) & \text{x is nice} \\L(x, y) & \text{x loves y}\end{array}Which of the followin...
1 1 vote
2 2 answers
451
451 views
Consider the following two logical equivalences that express 'logical laws':$\mathrm{\neg \forall_{x \in D} f \equiv \exists_{x \in D}\neg f}$$\neg(f \leftrightarrow g) \...
2 2 votes
1 1 answer
381
381 views
Consider the sentence:Nadhi eats a fruit only if the fruit is an apple.Define the propositional variables:$n$ : Nadhi eats a fruit.$a$ : The fruit is an apple.Which of th...
2 2 votes
2 2 answers
361
361 views
Let $\operatorname{Bird}(x)$ means " $x$ is a $\operatorname{bird}$" and $\mathrm{Fly(y)}$ means " $y$ can fly". Which of the following is a correct logical statement for...
2 2 votes
1 1 answer
603
603 views
Consider the following interpretation of a language with a unary predicates $P, Q$, and a binary predicate $R$.Universe $=\{1,2,3,4\}$$P=\{\langle 1\rangle,\langle 3\rang...
2 2 votes
1 1 answer
386
386 views
Suppose the marked diagram below conveys information about relationships between pirates, ruffians and scoundrels. We use shading to indicate that a region contains no el...
1 1 vote
1 1 answer
355
355 views
The statement form $(p \Leftrightarrow r) \Rightarrow(q \Leftrightarrow r)$ is equivalent to$[(\sim p \vee r) \wedge(p \vee \sim r)] \vee \sim[(\sim q \vee r) \wedge(q \v...
0 0 votes
1 1 answer
355
355 views
Which of the following formulas is a formalization of the sentence:"Every connected and circuit-free graph is a tree"Where $\operatorname{cir}(\mathrm{x})$ means " x has ...
1 1 vote
4 4 answers
629
629 views
Given the statement form below where $p, q, r, s$ are statement variables,$$\Biggl(\biggl(\Bigl((p \rightarrow q) \rightarrow(q \rightarrow r)\Bigl) \rightarrow(r \righta...
0 0 votes
2 2 answers
471
471 views
The island of Wantuutrewan is inhabited by exactly two types of natives: knights who always tell the truth and knaves who always lie. Every native is a knight or a knave,...
2 2 votes
2 2 answers
500
500 views
Given the following where $p, q, r, s, t$ are statement variables:(i) $(\sim r \rightarrow \sim r) \vee(\sim q \rightarrow q) \vee(t \rightarrow \sim t)$(ii) $(p \wedge q...