set L = PartialPredConnectivesLatt D;
thus PartialPredConnectivesLatt D is bounded ; :: according to PARTPR_1:def 17 :: thesis: ( PartialPredConnectivesLatt D is partially_complemented & PartialPredConnectivesLatt D is distributive )
thus PartialPredConnectivesLatt D is partially_complemented :: thesis: PartialPredConnectivesLatt D is distributive
proof end;
thus PartialPredConnectivesLatt D is distributive :: thesis: verum
proof
let a, b, c be Element of (PartialPredConnectivesLatt D); :: according to LATTICES:def 11 :: thesis: a "/\" (b "\/" c) = (a "/\" b) "\/" (a "/\" c)
reconsider a1 = a, b1 = b, c1 = c as PartialPredicate of D by PARTFUN1:46;
A1: ( a "/\" b = PP_and (a1,b1) & a "/\" c = PP_and (a1,c1) ) by Def11;
b "\/" c = PP_or (b1,c1) by Def12;
hence a "/\" (b "\/" c) = PP_and (a1,(PP_or (b1,c1))) by Def11
.= PP_or ((PP_and (a1,b1)),(PP_and (a1,c1))) by Th30
.= (a "/\" b) "\/" (a "/\" c) by A1, Def12 ;
:: thesis: verum
end;