theorem sem_if: ∀sig,M1,M2,M3,Rtrue,Rfalse,R2,R3,acc.
accRealize sig M1 acc Rtrue Rfalse → Realize sig M2 R2 → Realize sig M3 R3 →
Realize sig (ifTM sig M1 M2 M3 acc) (λt1,t2. (Rtrue ∘ R2) t1 t2 ∨ (Rfalse ∘ R3) t1 t2).
-
+#sig #M1 #M2 #M3 #Rtrue #Rfalse #R2 #R3 #acc #HaccR #HR2 #HR3 #t
+cases (HaccR t) #k1 * #outc1 * * #Hloop1 #HMtrue #HMfalse
+cases (true_or_false (cstate ?? outc1 == acc)) #Hacc
+ [cases (HR2 (ctape sig ? outc1)) #k2 * #outc2 * #Hloop2 #HM2
+ @(ex_intro … (k1+k2)) @(ex_intro … (lift_confR … (lift_confL … outc2)))
+%
+[@(loop_split ??????????? (loop_liftL … Hloop1))
+ [* *
+ [ #sl #tl whd in ⊢ (??%? → ?); #Hl %
+ | #sr #tr whd in ⊢ (??%? → ?); #Hr destruct (Hr) ]
+ ||4:cases outc1 #s1 #t1 %
+ |5:@(loop_liftR … Hloop2)
+ |whd in ⊢ (??(???%)?);whd in ⊢ (??%?);
+ generalize in match Hloop1; cases outc1 #sc1 #tc1 #Hloop10
+ >(trans_liftL_true sig M1 M2 ??)
+ [ whd in ⊢ (??%?); whd in ⊢ (???%);
+ @config_eq //
+ | @(loop_Some ?????? Hloop10) ]
+ ]
+| @(ex_intro … (ctape ? (seq sig M1 M2) (lift_confL … outc1)))
+ % //
+]
+qed.
(* We do not distinuish an input tape *)
record TM (sig:FinSet): Type[1] ≝