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4 (* ||A|| A project by Andrea Asperti *)
6 (* ||I|| Developers: *)
7 (* ||T|| The HELM team. *)
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15 include "lambda/ext.ma".
17 (* saturation conditions on an explicit subset ********************************)
19 definition SAT0 ≝ λP. ∀l,n. all P l → P (Appl (Sort n) l).
21 definition SAT1 ≝ λP. ∀l,i. all P l → P (Appl (Rel i) l).
23 definition SAT2 ≝ λ(P:?→Prop). ∀F,A,B,l. P B → P A →
24 P (Appl F[0:=A] l) → P (Appl (Lambda B F) (A::l)).
26 theorem SAT0_sort: ∀P,n. SAT0 P → P (Sort n).
27 #P #n #H @(H (nil ?) …) //
30 theorem SAT1_rel: ∀P,i. SAT1 P → P (Rel i).
31 #P #i #H @(H (nil ?) …) //
34 (* STRONGLY NORMALIZING TERMS *************************************************)
36 (* SN(t) holds when t is strongly normalizing *)
37 (* FG: we axiomatize it for now because we dont have reduction yet *)
40 definition CR1 ≝ λ(P:?→Prop). ∀M. P M → SN M.
42 axiom sn_sort: SAT0 SN.
44 axiom sn_rel: SAT1 SN.
46 axiom sn_lambda: ∀B,F. SN B → SN F → SN (Lambda B F).
48 axiom sn_beta: SAT2 SN.
50 (* FG: do we need this?
51 axiom sn_lift: ∀t,k,p. SN t → SN (lift t p k).