•Let qk be the
conjunction of all extension axioms with · k variables
•I.e. tt,s where t is a
type over x = (x1, …, xk)
•
•Lemma. Let A, B be
such that A ² qk, B ² qk . Then A =1wk B
•
•Proof: qk says precisely that the duplicator has a winning strategy with k pebbles.
•