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The formula  $\forall x \exists y \exists (\neg F(x,y,t))$ says that for every person $x$, there exists a person $y$, and there
 
The formula  $\forall x \exists y \exists (\neg F(x,y,t))$ says that for every person $x$, there exists a person $y$, and there
exists a time $t$, such that $x$ cannot fool $y$ at time t i.e. No person can fool everyone all the time. So option <b>(B)</b> is correct.
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exists a time $t$, such that $x$ cannot fool $y$ at time $t$ i.e., No person can fool everyone all the time. So option <b>(B)</b> is correct.
 
 
 
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[[Category: GATE2010]]
 
[[Category: GATE2010]]
[[Category: Logical Inference questions]]
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[[Category: Mathematical Logic questions from GATE]]

Latest revision as of 22:32, 16 April 2015

Suppose the predicate $F(x, y, t)$ is used to represent the statement that person $x$ can fool person $y$ at time $t$. which one of the statements below expresses best the meaning of the formula $\forall x \exists y \exists(\neg F(x,y,t))$?


(A) Everyone can fool some person at some time

(B) No one can fool everyone all the time

(C) Everyone cannot fool some person all the time

(D) No one can fool some person at some time

Solution by Happy Mittal

The formula $\forall x \exists y \exists (\neg F(x,y,t))$ says that for every person $x$, there exists a person $y$, and there exists a time $t$, such that $x$ cannot fool $y$ at time $t$ i.e., No person can fool everyone all the time. So option (B) is correct.




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Suppose the predicate $F(x, y, t)$ is used to represent the statement that person $x$ can fool person $y$ at time $t$. which one of the statements below expresses best the meaning of the formula $\forall x \exists y \exists(\neg F(x,y,t))$?


(A) Everyone can fool some person at some time

(B) No one can fool everyone all the time

(C) Everyone cannot fool some person all the time

(D) No one can fool some person at some time

Solution by Happy Mittal[edit]

The formula $\forall x \exists y \exists (\neg F(x,y,t))$ says that for every person $x$, there exists a person $y$, and there exists a time $t$, such that $x$ cannot fool $y$ at time t i.e. No person can fool everyone all the time. So option (B) is correct.




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