Telephone wires are visible.
Telephone wires are not invisible.
Not invisible means the same thing as visible.
exists s1 x1 x2.(Theme(s1,x1) & a_visible(s1) & n_wire(x1) & (x1 = x2) & ne_nam_telephone(x2))
exists x1 x2.(-exists s1.(Theme(s1,x1) & a_invisible(s1)) & n_wire(x1) & (x1 = x2) & ne_nam_telephone(x2))