(* Basic_1: was: csubc_drop1_conf_rev *)
lemma drops_lsubc_trans: ∀RR,RS,RP. gcp RR RS RP →
- â\88\80G,L1,K1,des. â\87©*[Ⓕ, des] L1 ≡ K1 → ∀K2. G ⊢ K1 ⫃[RP] K2 →
- â\88\83â\88\83L2. G â\8a¢ L1 â«\83[RP] L2 & â\87©*[Ⓕ, des] L2 ≡ K2.
+ â\88\80G,L1,K1,des. â¬\87*[Ⓕ, des] L1 ≡ K1 → ∀K2. G ⊢ K1 ⫃[RP] K2 →
+ â\88\83â\88\83L2. G â\8a¢ L1 â«\83[RP] L2 & â¬\87*[Ⓕ, des] L2 ≡ K2.
#RR #RS #RP #Hgcp #G #L1 #K1 #des #H elim H -L1 -K1 -des
[ /2 width=3 by drops_nil, ex2_intro/
| #L1 #L #K1 #des #d #e #_ #HLK1 #IHL #K2 #HK12