DEFINITION sty1_trans()
TYPE =
∀g:G.∀c:C.∀t1:T.∀t:T.(sty1 g c t1 t)→∀t2:T.(sty1 g c t t2)→(sty1 g c t1 t2)
BODY =
assume g: G
assume c: C
assume t1: T
assume t: T
suppose H: sty1 g c t1 t
assume t2: T
suppose H0: sty1 g c t t2
we proceed by induction on H0 to prove sty1 g c t1 t2
case sty1_sty0 : t3:T H1:sty0 g c t t3 ⇒
the thesis becomes sty1 g c t1 t3
by (sty1_sing . . . . H . H1)
sty1 g c t1 t3
case sty1_sing : t0:T :sty1 g c t t0 t3:T H3:sty0 g c t0 t3 ⇒
the thesis becomes sty1 g c t1 t3
(H2) by induction hypothesis we know sty1 g c t1 t0
by (sty1_sing . . . . H2 . H3)
sty1 g c t1 t3
we proved sty1 g c t1 t2
we proved ∀g:G.∀c:C.∀t1:T.∀t:T.(sty1 g c t1 t)→∀t2:T.(sty1 g c t t2)→(sty1 g c t1 t2)