Given a set X and a function h:X⟶{0,1} which labels each
element of X with either 0 or 1, we may define a function h(s) to
measure the similarity of pairs of points in X according to h.
Specifically, for h∈{0,1}X we define h(s)∈{0,1}X×X
by h(s)(w,x):=1[h(w)=h(x)]. This idea can be extended to a set
of functions, or hypothesis space H⊆{0,1}X by defining
a similarity hypothesis space H(s):={h(s):h∈H}.
We show that vc−dimension(H(s))∈Θ(vc−dimension(H)).