let L be non empty LattStr ; ( L is meet-idempotent & L is meet-associative & L is meet-commutative & L is satisfying_QLT1 & L is join-idempotent & L is join-associative & L is join-commutative & L is satisfying_QLT2 & L is QLT-selfmodular implies L is modular )
assume A1:
( L is meet-idempotent & L is meet-associative & L is meet-commutative & L is satisfying_QLT1 & L is join-idempotent & L is join-associative & L is join-commutative & L is satisfying_QLT2 & L is QLT-selfmodular )
; L is modular
then
( ( for v0 being Element of L holds v0 "/\" v0 = v0 ) & ( for v2, v1, v0 being Element of L holds (v0 "/\" v1) "/\" v2 = v0 "/\" (v1 "/\" v2) ) & ( for v1, v0 being Element of L holds v0 "/\" v1 = v1 "/\" v0 ) & ( for v0, v2, v1 being Element of L holds (v0 "/\" (v1 "\/" v2)) "\/" (v0 "/\" v1) = v0 "/\" (v1 "\/" v2) ) & ( for v0 being Element of L holds v0 "\/" v0 = v0 ) & ( for v2, v1, v0 being Element of L holds (v0 "\/" v1) "\/" v2 = v0 "\/" (v1 "\/" v2) ) & ( for v1, v0 being Element of L holds v0 "\/" v1 = v1 "\/" v0 ) & ( for v0, v2, v1 being Element of L holds (v0 "\/" (v1 "/\" v2)) "/\" (v0 "\/" v1) = v0 "\/" (v1 "/\" v2) ) & ( for v2, v1, v0 being Element of L holds (v0 "/\" v1) "\/" (v2 "/\" (v0 "\/" v1)) = (v0 "\/" v1) "/\" (v2 "\/" (v0 "/\" v1)) ) )
by LATTICES:def 4, LATTICES:def 5, LATTICES:def 6, LATTICES:def 7, SHEFFER1:def 9, ROBBINS1:def 7;
then
for v1, v2, v3 being Element of L holds (v1 "/\" v2) "\/" (v1 "/\" v3) = v1 "/\" (v2 "\/" (v1 "/\" v3))
by ThQLT5;
hence
L is modular
by ModRedef, A1; verum