for D being non empty compact non horizontal non vertical Subset of (TOP-REAL 2)
for a being Real
for p being Point of (TOP-REAL 2) st a > 0 & p in L~ (SpStSeq D) holds
ex q being Point of (TOP-REAL 2) st
( q in BDD (L~ (SpStSeq D)) & |.(p - q).| < a )