let L be non empty satisfying_Sheffer_1 satisfying_Sheffer_2 satisfying_Sheffer_3 ShefferStr ; :: thesis: for w, p being Element of L holds (p | w) | (w | w) = w
let w, p be Element of L; :: thesis: (p | w) | (w | w) = w
(w | w) | (p | w) = (p | w) | (w | w) by Th83;
hence (p | w) | (w | w) = w by Th121; :: thesis: verum