16
Extension Axioms
•
Definition
Type s(
x
, z)
extends
the type t(
x
) if
{s, t} is consistent;
•
Equivalently: every conjunct in t occurs in s
•
•
Definition
The
extension axiom
for types t, s
is the formula
t
t,s
=
8
x
1
…
8
x
k
(t(
x
)
)
9
z.s(
x
, z))