•One of several combinatoric methods for proving EF games formally
•
•Definition. Let A be a
structure. The Gaifman graph G(A) = (A, EA) is s.t.
(a,b)
2 EA iff 9 tuple t in A containing both a and b
•
•Definition. The r-sphere,
for r > 0, is:
• S(r,a) := {b 2 A | d(a,b) · r}