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Term = function (term1,....termn) or constant or variables
•  A logical expression that refers to an object
- LeftLegOf (Richard)
• There are 2 kinds of terms:
- Constant symbols: Table, Computer
- Function symbols: LeftLeg(Pete), Sqrt(3), Plus(2,3) etc

Atomic Sentence  =    predicate (term1,.....,termn)
or term1 = term2
An atomic sentence is formed from a predicate symbol followed by list of terms.

Examples:
LargeThan(2,3) is false.
Brother_of(Mary,Pete) is false.
Married(Father(Richard),Mother(John)) could be true or false.

Note: Functions do not state facts and form no sentence:
- Brother(Pete) refers to John (his brother) and is neither true nor false

Brother_of(Pete,Brother(Pete)) is True.
Binary relation            Function

Complex Sentences

We make complex sentence with connectives (just like in propositional logic).

More Examples
• Brother(Richard, John) ∧ Brother(John, Richard)
• King(Richard) ∨ King (john)
• King(John)=> á†¨King(Richard)
• LessThan(plus(1,2),4)∧GreaterThan(1,2)
(Semantics are the same as in Propositional logic)

Variables
• Person(John) is true or false because we give it a single argument 'John'
• We can be much more flexible if we allow variables which can take on values in a domain. e.g., all person x, all integers i, etc.
- E.g., can state rules like Person(x) => HasHead(x)
or Integer(i) => Integer(plus(i,1)