-definition dfr (p) (q): relation2 prototerm prototerm ≝
- λt1,t2. ∃k:pnat.
- let r ≝ p●𝗔◗𝗟◗q in
- ∧∧ 𝗟◗q = ↳[k](𝗟◗q) & r◖𝗱k ϵ t1 &
- t1[⋔r←𝛕k.(t1⋔(p◖𝗦))] ⇔ t2
+definition dfr (r): relation2 prototerm prototerm ≝
+ λt1,t2.
+ ∃∃p,q,n. p●𝗔◗𝗟◗q = r &
+ q ϵ 𝐂❨Ⓕ,n❩ & r◖𝗱↑n ϵ t1 &
+ t1[⋔r←𝛕↑n.(t1⋔(p◖𝗦))] ⇔ t2