let L be B_Lattice; :: thesis: for X, Y being Element of L holds X ` [= (X "/\" Y) `
let X, Y be Element of L; :: thesis: X ` [= (X "/\" Y) `
X ` [= (X `) "\/" (Y `) by LATTICES:5;
hence X ` [= (X "/\" Y) ` by LATTICES:23; :: thesis: verum