= y == x = y
t,x:Term. (t = x) 
Prop
f(t))t:Term. s(t) Termt,r:Term. SUBX(t; r) Term| Some definitions of interest. | |
| repst | Def x = y == x = y |
| Thm* t,x:Term. (t = x) Prop | |
| s | Def s(t) == SUBX(f(t); f(t)) |
| Thm* t:Term. s(t) Term | |
| subx | Def SUBX(t; e) == t[e/X] |
| Thm* t,r:Term. SUBX(t; r) Term |
About:
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