Beispiel 1:
σ1 = {X Y}, σ2 = {Y
a}, σ1oσ2 = {X
a, Y
a}.
Beispiel 2 (nachrechnen!):
σ1 = {X Y}, σ2 = {Y
X}, σ1oσ2 = σ2
Eigenschaften:
Implementierung:
import Data.Map type Substitution = Map Identifier Term times :: Substitution -> Substitution -> Substition