reconsider S = {} as Subset of W by XBOOLE_1:2;
take S ; :: thesis: for p, q being FinSequence of NAT st p in S & q in S holds
p,q are_c=-comparable
let p, q be FinSequence of NAT ; :: thesis: ( p in S & q in S implies p,q are_c=-comparable )
thus ( p in S & q in S implies p,q are_c=-comparable ) ; :: thesis: verum