consider u being BinOp of (bool {} );
take \/-SemiLattStr(# (bool {} ),u #) ; :: thesis: ( \/-SemiLattStr(# (bool {} ),u #) is strict & not \/-SemiLattStr(# (bool {} ),u #) is empty )
thus ( \/-SemiLattStr(# (bool {} ),u #) is strict & not \/-SemiLattStr(# (bool {} ),u #) is empty ) ; :: thesis: verum