Lemma 4 Given a relation r and an arbitrary, but
fixed tuple t ∈ r, form the set
M = {(t, α, {s ∈ r|α `t s})}
where the minterm α is word in {0, 1}
n. Any tuple
s ∈ r belongs to one and only one implicant.
Proof Assume the contrary, that s belongs to two
different implicants. The implicants’ minterms must
disagree on at least one symbol at position i. Then
s.Ai will either agree with t.Ai and s will belong to
the minterm with αi = 1, or the converse; but not
both.