Logical Equivalence of x <=> y and (x-->y) ^ ((~x)-->(~y))

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In summary, proving x <=> y is logically equivalent to (x-->y) ^ ((~x)-->(~y)) can be done by rewriting one of the subexpressions of x <=> y and using a truth table. The contrapositive of ~x=>~y can also be used in the proof.
  • #1
aorick21
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Prove x <=> y is logically equivalent to (x-->y) ^ ((~x)-->(~y)).
 
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  • #2
aorick21 said:
Prove x <=> y is logically equivalent to (x-->y) ^ ((~x)-->(~y)).

Please show some sort of work or at least tell us where you are stuck. We help with your homework, not do your homework.
 
  • #3
Actually, [itex]x \Leftrightarrow y[/itex] is shorthand for a longer expression. Which one? Now rewrite one of the subexpressions and you're done.

If you want more specific help, please refer to l46kok's post.

Also, how specific do you need the proof to be? Can you use "intuitive" rules or do you really have to produce a proof tree?
 
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  • #4
I'd just use a truth table.

If you don't know what that is, then I don't think you belong in math.
 
  • #5
TimNguyen said:
I'd just use a truth table.

If you don't know what that is, then I don't think you belong in math.

Rubbish. If you do know what one is then perhaps you belong in computer science or electrical engineering?
 
  • #6
Aoik: what is the contrapositive of ~x=>~y

p.s.: Matt, you crack me up.
 

FAQ: Logical Equivalence of x <=> y and (x-->y) ^ ((~x)-->(~y))

What is logical equivalence?

Logical equivalence refers to the relationship between two statements or propositions that have the same truth value. This means that if one statement is true, the other statement will also be true, and if one statement is false, the other statement will also be false.

What is the meaning of x <=> y?

The statement x <=> y means that x and y are logically equivalent. This means that x and y have the same truth value and can be substituted for each other in any logical expression without changing its truth value.

What is the meaning of (x-->y) ^ ((~x)-->(~y))?

This expression is a logical statement that is equivalent to x <=> y. It is read as "if x implies y, and if not x implies not y." This means that if x is true, then y must also be true, and if x is false, then y must also be false.

How can the logical equivalence of x <=> y and (x-->y) ^ ((~x)-->(~y)) be proven?

The logical equivalence of x <=> y and (x-->y) ^ ((~x)-->(~y)) can be proven by constructing a truth table for both statements. The truth table will show that the two statements have the same truth values for all possible combinations of truth values for x and y.

What is the practical application of understanding logical equivalence?

Understanding logical equivalence is important in fields such as mathematics, computer science, and philosophy. It allows us to simplify complex logical expressions and to prove the validity of arguments and statements. It also helps in identifying logical fallacies and inconsistencies in reasoning.

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