let H be ZF-formula; :: thesis: for x, y, z being Variable
for M being non empty set st M |= H holds
M |= Ex x,y,z,H
let x, y, z be Variable; :: thesis: for M being non empty set st M |= H holds
M |= Ex x,y,z,H
let M be non empty set ; :: thesis: ( M |= H implies M |= Ex x,y,z,H )
( M |= H implies M |= Ex y,z,H ) by Th107;
hence ( M |= H implies M |= Ex x,y,z,H ) by Th105; :: thesis: verum