## What is tautology and contradiction in math?

1. A compound statement which is always true is called a tautology , while a compound statement which is always false is called a contradiction . 🔗

## What is WFF math?

In mathematical logic, propositional logic and predicate logic, a well-formed formula, abbreviated WFF or wff, often simply formula, is a finite sequence of symbols from a given alphabet that is part of a formal language. A formal language can be identified with the set of formulas in the language.

What is tautology and satisfiable?

A compound proposition P is a tautology if every truth assignment satisfies P, i.e. all entries of its truth table are true. A compound proposition P is satisfiable if there is a truth assignment that satisfies P; that is, at least one entry of its truth table is true.

What is satisfiability in discrete mathematics?

Satisfiability refers to the existence of a combination of values to make the expression true. So in short, a proposition is satisfiable if there is at least one true result in its truth table, valid if all values it returns in the truth table are true .

### What is WFF give example?

A Statement variable standing alone is a Well-Formed Formula(WFF). For example– Statements like P, ∼P, Q, ∼Q are themselves Well Formed Formulas. If ‘P’ is a WFF then ∼P is a formula as well. If P & Q are WFFs, then (P∨Q), (P∧Q), (P⇒Q), (P⇔Q), etc.

### How do you identify a WFF?

It has only three rules:

1. Any capital letter by itself is a WFF.
2. Any WFF can be prefixed with “~”. (The result will be a WFF too.)
3. Any two WFFs can be put together with “•”, “∨”, “⊃”, or “≡” between them, enclosing the result in parentheses. (This will be a WFF too.)

What is the satisfiability problem?

Boolean Satisfiability Problem Boolean Satisfiability or simply SAT is the problem of determining if a Boolean formula is satisfiable or unsatisfiable. Satisfiable : If the Boolean variables can be assigned values such that the formula turns out to be TRUE, then we say that the formula is satisfiable.

How do you write a wff?

## How do you prove wff?

Well-formed formulas will be called “wffs”. Rule (1) A variable standing alone is a wff. Rule (2) If p is a wff, so is ~p. Rule (3) If p and q are wffs, (p∧q), (p∨q), (pÉq), and (p⇔q) are wffs….Valid wffs.

Law wff
(p∨q) ⇔ ~(~p.~q)
Commutative Laws (p∨q) ⇔ (q∨p)
(p.q) ⇔ (q.p)
Associative Laws [(p∨q)∨r] ⇔ [p∨(q∨r)]

## What is wff give example?

Is P & Q a wff?

This is a wff: p∧(q∨r). So there are an infinite number of formulas that are not wffs, just as there are an infinite number that are wffs….Valid wffs.

Law wff
De Morgan Laws (p.q) ⇔ ~(~p ∨ ~q)
(p∨q) ⇔ ~(~p.~q)
Commutative Laws (p∨q) ⇔ (q∨p)
(p.q) ⇔ (q.p)

What is tautology and example?

Tautology is the use of different words to say the same thing twice in the same statement. ‘The money should be adequate enough’ is an example of tautology. Synonyms: repetition, redundancy, verbiage, iteration More Synonyms of tautology. COBUILD Advanced English Dictionary.

### Which formula is a tautology?

In mathematical logic, a tautology (from Greek: ταυτολογία) is a formula or assertion that is true in every possible interpretation. An example is “x=y or x≠y”. Similarly, “either the ball is green, or the ball is not green” is always true, regardless of the colour of the ball.

### Is Pvq → q tautology?

Look at the following two compound propositions: p → q and q ∨ ¬p. (p → q) and (q ∨ ¬p) are logically equivalent. So (p → q) ↔ (q ∨ ¬p) is a tautology.

What are the rules of wff?

It has only three rules:

• Any capital letter by itself is a WFF.
• Any WFF can be prefixed with “~”. (The result will be a WFF too.)
• Any two WFFs can be put together with “•”, “∨”, “⊃”, or “≡” between them, enclosing the result in parentheses. (This will be a WFF too.)

What is the difference between tautology and satisfiable?

Satisfiable can be a tautology or even if there is one True value in the truth table. Eg. p or (not p) is tautology and not (p implies q) has one True.

## What is a tautology in math?

Tautologies are typically found in the branch of mathematics called logic. They use their own special symbols: p p, ~p ~ p and q q all signify the statements, with p p generally reserved for the first one and either ~p ~ p or q q for the second statement. You can “translate” tautologies from ordinary language into mathematical expressions.

## Is a tautology always true?

No matter what the individual parts are, the result is a true statement; a tautology is always true. The opposite of a tautology is a contradiction or a fallacy, which is “always false”.

What is the difference between satisfiable and unsatisfiable truth tables?

Unsatisfiable means the truth table is a contradiction. ie. A wff which is not valid is unsatisfiable. Eg. p and (not p) Satisfiable can be a tautology or even if there is one True value in the truth table. Eg. p or (not p) is tautology and not (p implies q) has one True. So, they are satisfiable.