Predicate Logic

Substitution and Unification
Union of θ and δ:
θδ is calculated as follows:
1. Apply δ to denominator of θ:
{x 1/t 1δ, x 2/t 2δ, .., x n/t nδ}
2. Remove all the form: x i /x i from 1.
3. Remove from δ the form: y i /s i
if y i ∈ {x 1 ,x 2 , .., x n }
4. θδ = union( line 2 and 3)
Artificial Intelligence: Predicate Logic Slide: 64