theorem Th150: :: SHEFFER2:150

for L being non empty satisfying_Sheffer_1 satisfying_Sheffer_2 satisfying_Sheffer_3 ShefferStr
for p, z, y, x being Element of L holds z | (x | p) = (((p | p) | z) | ((x | (y | (y | y))) | z)) | (((p | p) | z) | ((x | (y | (y | y))) | z))