Added substitution lemma for equivalence calculations
Added substitution lemma for equivalence calculations

javra/lean,leodemoura/lean,htzh/lean,javra/lean,c-cube/lean,c-cube/lean,soonhokong/lean-osx,leanprover-community/lean,UlrikBuchholtz/lean,dselsam/lean,Kha/lean,soonhokong/lean-osx,levnach/lean,sp3ctum/lean,johoelzl/lean,htzh/lean,eigengrau/lean,leanprover/lean,soonhokong/lean,fgdorais/lean,Kha/lean,fgdorais/lean,digama0/lean,leanprover-community/lean,rlewis1988/lean,leanprover/lean,sp3ctum/lean,levnach/lean,avigad/lean,UlrikBuchholtz/lean,soonhokong/lean,johoelzl/lean,soonhokong/lean-osx,UlrikBuchholtz/lean,UlrikBuchholtz/lean,johoelzl/lean,digama0/lean,digama0/lean,dselsam/lean,rlewis1988/lean,eigengrau/lean,soonhokong/lean-windows,dselsam/lean,avigad/lean,fgdorais/lean,avigad/lean,leanprover-community/lean,fpvandoorn/lean2,eigengrau/lean,leanprover/lean,fpvandoorn/lean,digama0/lean,leodemoura/lean,johoelzl/lean,leanprover/lean,htzh/lean,leanprover/lean,dselsam/lean,javra/lean,soonhokong/lean-windows,Kha/lean,eigengrau/lean,levnach/lean,fpvandoorn/lean,digama0/lean,sp3ctum/lean,leodemoura/lean,fpvandoorn/lean,fpvandoorn/lean2,fpvandoorn/lean,leodemoura/lean,soonhokong/lean-osx,fpvandoorn/lean2,levnach/lean,Kha/lean,soonhokong/lean-windows,soonhokong/lean,levnach/lean,leanprover-community/lean,sp3ctum/lean,avigad/lean,rlewis1988/lean,fgdorais/lean,dselsam/lean,soonhokong/lean,avigad/lean,c-cube/lean,soonhokong/lean-osx,sp3ctum/lean,javra/lean,avigad/lean,javra/lean,Kha/lean,rlewis1988/lean,c-cube/lean,Kha/lean,UlrikBuchholtz/lean,soonhokong/lean,eigengrau/lean,leodemoura/lean,rlewis1988/lean,c-cube/lean,johoelzl/lean,johoelzl/lean,soonhokong/lean-windows,leanprover/lean,fpvandoorn/lean,leanprover-community/lean,htzh/lean,leodemoura/lean,rlewis1988/lean,fpvandoorn/lean,fpvandoorn/lean2,leanprover-community/lean,fpvandoorn/lean2,fgdorais/lean,digama0/lean,dselsam/lean,fgdorais/lean,soonhokong/lean-windows,htzh/lean