question: public boolean isSubspace ( Subspace subspace ) { if ( this . dimensionality > subspace . dimensionality ) { return false ; } for ( int d = BitsUtil . nextSetBit ( dimensions , 0 ) ; d >= 0 ; d = BitsUtil . nextSetBit ( dimensions , d + 1 ) ) { if ( ! BitsUtil . get ( subspace . dimensions , d ) ) { return false ; } } return true ; }
target:  Returns true if this subspace is a subspace of the specified subspace, i.e. if the set of dimensions building this subspace are contained in the set of dimensions building the specified subspace.