definition dfr (p) (q): relation2 prototerm prototerm ≝
λt1,t2. ∃∃b,n.
let r ≝ p●𝗔◗b●𝗟◗q in
- â\88§â\88§ â\8a\97b ϵ ð\9d\90\81 & â\9d\98qâ\9d\98 = (â\86\91[q]ð\9d\90¢)@❨n❩ & r◖𝗱n ϵ t1 &
+ â\88§â\88§ â\8a\97b ϵ ð\9d\90\81 & â\88\80f. â\9d\98qâ\9d\98 = (â\86\91[q]⫯f)@❨n❩ & r◖𝗱n ϵ t1 &
t1[⋔r←𝛗n.(t1⋔(p◖𝗦))] ⇔ t2
.