# Equivalence laws

Propositional Logic Equivalence Laws

• Equivalence statements. Two statements are said to be equivalent if they have the same truth value. Following are two statements.
• Properties of 0
• Properties of 1
• Involution
• Idempotence Law
• Absorption Law
• Complementarity Law
• Commutative Law
• Associative Law
• Distributive Law

More items…

Two statements are logically equivalent if, and only if, their resulting forms are logically equivalent when identical statement variables are used to represent component statements.

## What are the laws of equivalence in philosophy?

Propositional Logic Equivalence Laws 1 Equivalence statements. Two statements are said to be equivalent if they have the same truth value. Following are two statements. 2 Properties of 0 3 Properties of 1 4 Involution 5 Idempotence Law 6 Absorption Law 7 Complementarity Law 8 Commutative Law 9 Associative Law 10 Distributive Law More items…

## What is logical equivalence?

Logical equivalence is different from material equivalence, although the two concepts are intrinsically related. In logic, many common logical equivalences exist and are often listed as laws or properties. The following tables illustrate some of these. The following statements are logically equivalent:

## What are the 1st 1 equivalent statements?

1 Equivalence statements. Two statements are said to be equivalent if they have the same truth value. Following are two statements. 2 Properties of 0 3 Properties of 1 4 Involution 5 Idempotence Law 6 Absorption Law 7 Complementarity Law 8 Commutative Law 9 Associative Law 10 Distributive Law More items…

## How do you prove equivalence in math?

And the easiest way to show equivalence is to create a truth table and see if the columns are identical, as the example below nicely demonstrates Below is a list of important equivalences laws, sometimes called the law of the algebra of propositions, that we will use throughout this course.

## How can we use equivalence law?

4:325:18Prove Logical Equivalence Using Laws – YouTubeYouTubeStart of suggested clipEnd of suggested clipLaw to rearrange them and if you remember commutative law P or Q is logically equivalent to Q or P.MoreLaw to rearrange them and if you remember commutative law P or Q is logically equivalent to Q or P. In. This case we have Q or P. So we can switch them back around to P or Q. – P or Q.

## How do you prove logical equivalence with laws?

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.

## What is equivalence law in discrete mathematics?

Two propositions p and q are logically equivalent if their truth tables are the same. Namely, p and q are logically equivalent if p ↔ q is a tautology. If p and q are logically equivalent, we write p ≡ q. c Xin He (University at Buffalo)

## What are the examples of logical equivalence?

Now, consider the following statement: If Ryan gets a pay raise, then he will take Allison to dinner. This means we can also say that If Ryan does not take Allison to dinner, then he did not get a pay raise is logically equivalent.

## Which is logically equivalent to P ∧ q → R?

(p ∧ q) → r is logically equivalent to p → (q → r).

## Are the statements P → q ∨ R and P → q ∨ P → are logically equivalent?

Since columns corresponding to p∨(q∧r) and (p∨q)∧(p∨r) match, the propositions are logically equivalent. This particular equivalence is known as the Distributive Law.

## What equivalence means?

Definition of equivalence 1a : the state or property of being equivalent. b : the relation holding between two statements if they are either both true or both false so that to affirm one and to deny the other would result in a contradiction. 2 : a presentation of terms as equivalent.

## What is equivalent formula?

In predicate logic, two formulas are logically equivalent if they have the same truth value for all possible predicates. Consider ¬(∀xP(x)) and ∃x(¬P(x)). These formulas make sense for any predicate P, and for any predicate P they have the same truth value.

## How do you prove equivalence?

To prove an equivalence relation, you must show reflexivity, symmetry, and transitivity, so using our example above, we can say: Reflexivity: Since a – a = 0 and 0 is an integer, this shows that (a, a) is in the relation; thus, proving R is reflexive. Symmetry: If a – b is an integer, then b – a is also an integer.

## What are the laws of logic?

The three laws of logic are: The Law of Identity states that when something is true it is identical to itself and nothing else, S = S. The Law of Non-Contradiction states that when something is true it cannot be false at the same time, S does not = P.

## What is meant by 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 syllogism law?

In mathematical logic, the Law of Syllogism says that if the following two statements are true: (1) If p , then q . (2) If q , then r . Then we can derive a third true statement: (3) If p , then r .

## What are the laws for logical equivalences?

Some Laws of Logical EquivalenceIdempotent Laws. (i) p ∨ p ≡ p. … Commutative Laws. (i) p ∨ q ≡ q ∨ p. … Associative Laws. (i) p ∨ ( q ∨ r ) ≡ ( p ∨ q ) ∨ r (ii) p ∧ ( q ∧ r ) ≡ ( p ∧ q ) ∧ r .Distributive Laws. … Identity Laws. … Complement Laws. … Involution Law or Double Negation Law. … 8. de Morgan’s Laws.More items…•

## How do you prove three statements are logically equivalent?

2:015:293 Ways to Show a Logical Equivalence | Ex: DeMorgan’s LawsYouTubeStart of suggested clipEnd of suggested clipTrue. That that means these two different sides are logically equivalent by definition. So this isMoreTrue. That that means these two different sides are logically equivalent by definition. So this is the more formal proof of the reasonable. Test that are sort of English sentences.

## How do you know if something is logically equivalent?

Logical equivalence occurs when two statements have the same truth value. This means that one statement can be true in its own context, and the second statement can also be true in its own context, they just both have to have the same meaning.

## How do you prove equivalency?

Equivalence does not mean identical. It means the difference is less than some predetermined difference Δ. Demonstrating equivalence requires defining a difference Δ that is considered significant and then demonstrating with high confidence the difference is less than Δ.

## What is the logical equivalent of A and B?

The logical equivalence of the statements A and B is denoted by A ≡ B or A ⇔ B .

## Is tautology logically equivalent to A and B?

From the definition, it is clear that, if A and B are logically equivalent, then A ⇔ B must be tautology .

## Logical equivalences

In logic, many common logical equivalences exist and are often listed as laws or properties. The following tables illustrate some of these.

## Relation to material equivalence

Logical equivalence is different from material equivalence. Formulas
p {\displaystyle p}
and
q {\displaystyle q}
are logically equivalent if and only if the statement of their material equivalence (
p ⟺ q {\displaystyle p\iff q}
) is a tautology.

## What is a compound proposition that is neither a tautology nor a contradiction?

And a compound proposition that is neither a tautology nor a contradiction is referred to as a contingency.

## What is the negation of De Morgan’s law?

Using De Morgan’s Laws, we can express the negation as “I’m not eating out at a restaurant, or I’m not going dancing.”

## Why are tautologies and contradictions 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.

## Do compound propositions have equivalences?

Similarly, there are some very useful equivalences for compound propositions involving implications and biconditional statements, as seen below.

## Properties of 0

• If x is a statement then, 0 + x = x 0 . x = 0 where + is the OR operator and . is the AND operator Truth table

## Properties of 1

• If x is a statement then, 1 + x = 1 1 . x = x where + is the OR operator and . is the AND operator Truth table

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## Idempotence Law

• If p is a statement then, p + p = p p . p = p where + is the OR operator and . is the AND operator Truth table

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## Absorption Law

• If p and q are two statements then, p + (p.q) = p p . (p + q) = p where + is the OR operator and . is the AND operator Truth table

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## Complementarity Law

• If p is a statement then, p + (~p) = 1 p . (~p) = 0 where + is the OR operator, . is the AND operator and ~ is the NOT operator Truth table

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## Commutative Law

• If p and q are two statements then, p + q = q + p p . q = q . p where + is the OR operator and . is the AND operator

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## Associative Law

• If p, q and r are three statements then, (p + q) + r = p + (q + r) (p . q) . r = p . (q . r) where + is the OR operator and . is the AND operator

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## Distributive Law

• If p, q and r are three statements then, p . (q + r) = (p . q) + (p . r) p + (q . r) = (p + q) . (p + r) p + (~p . q) = p + q where + is the OR operator, . is the AND operator and ~ is the NOT operator

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## de Morgan’s Law

• If p and q are two statements then, ~(p + q) = ~p . ~q ~(p . q) = ~p + ~q where + is the OR operator, . is the AND operator and ~ is the NOT operator Truth table

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