Logical difference between ‘equivalence’ and ‘an absence of differences’


What is difference between logical and equivalence?

Logical equivalence is different from material equivalence. Formulas P and Q are logically equivalent if and only if the statement of their material equivalence (P ↔ Q) is a tautology. There is a difference between being true and being a tautology.

What is the meaning of logical equivalence?

Logical equivalence is a type of relationship between two statements or sentences in propositional logic or Boolean algebra. The relation translates verbally into “if and only if” and is symbolized by a double-lined, double arrow pointing to the left and right ( ).

What is logical equivalence in philosophy?

Logical equivalence. Definition: a pair of sentences are logically equivalent if and only if it is not possible for one of the sentences to be true while the other sentence is false. A pair of sentences may turn out true under exactly the same circumstances.

What does logically equivalent mean example?

Two expressions are logically equivalent provided that they have the same truth value for all possible combinations of truth values for all variables appearing in the two expressions. In this case, we write X≡Y and say that X and Y are logically equivalent.

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What is equivalence and laws of equivalence?

Two logical statements are logically equivalent if they always produce the same truth value. Consequently, p≡q is same as saying p⇔q is a tautology. Beside distributive and De Morgan’s laws, remember these two equivalences as well; they are very helpful when dealing with implications. p⇒q≡¯q⇒¯pandp⇒q≡¯p∨q.

Can two false sentences be logically equivalent?

No two false sentences are logically equivalent. circumstances. A pair of equivalent sentences must both be false at the same time if they are false at all.

Why is logical equivalence important?

Because tautologies and contradictions are essential in proving or verifying mathematical arguments, they help us to explain propositional equivalences — statements that are equal in logical argument. And it will be our job to verify that statements, such as p and q, are logically equivalent.

What is logically equivalent to an IF THEN statement?

A conditional statement is logically equivalent to its contrapositive. Converse: Suppose a conditional statement of the form “If p then q” is given. The converse is “If q then p.” Symbolically, the converse of p q is q p.

What is logically equivalent to P and Q?

The propositions are equal or logically equivalent if they always have the same truth value. That is, p and q are logically equivalent if p is true whenever q is true, and vice versa, and if p is false whenever q is false, and vice versa.



Logical Arguments as Compound Propositions.

p q [(p → !q) & (!p) ] → q
F F F

What makes two statements logically equivalent?

Two statement forms are logically equivalent if, and only if, their resulting truth tables are identical for each variation of statement variables. p q and q p have the same truth values, so they are logically equivalent.

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How do you find the logical equivalence without truth tables?

Quote from the video:
Youtube quote: So there's a complete proof that the negation of P implies not Q is actually equivalent to P and Q.