theorem JoinAssoc: :: ROBBINS5:8

for L being non empty LattStr st L is join-absorbing & ( for v0, v2, v1 being Element of L holds v0 "/\" (v1 "\/" v2) = (v2 "/\" v0) "\/" (v1 "/\" v0) ) holds
for v0, v1, v2 being Element of L holds (v0 "\/" v1) "\/" v2 = v0 "\/" (v1 "\/" v2)