@Override
    public int composePair(int a, int b) {
        return (set.contains(a) && set.contains(b)) ? norm2.composePair(a, b) : -1;
    }
@ Override public int composePair ( int a , int b ) { return ( set . contains ( a ) && set . contains ( b ) ) ? norm2 . composePair ( a , b ) : - 1 ; }
{@inheritDoc}