Remove useless type class instance.

ada321d1 · Robbert Krebbers · cdb38447 · ada321d1
Commit ada321d1 authored Jun 30, 2016 by Robbert Krebbers
--- a/algebra/dec_agree.v
+++ b/algebra/dec_agree.v
@@ -18,7 +18,6 @@ Context {A : Type} `{∀ x y : A, Decision (x = y)}.

 Instance dec_agree_valid : Valid (dec_agree A) := λ x,
  if x is DecAgree _ then True else False.
-Instance dec_agree_equiv : Equiv (dec_agree A) := equivL.
 Canonical Structure dec_agreeC : cofeT := leibnizC (dec_agree A).

 Instance dec_agree_op : Op (dec_agree A) := λ x y,