public int compareTo( MUM other ) 
	{
		if ( other == null )
			return 0;	// what else can we do??
		else if ( match.length < other.match.length )
			return 1;
		else if ( match.length > other.match.length )
			return -1;
		// prefer direct alignments to transpositions
		else if ( transposed && !other.transposed )
			return 1;
		else if ( !transposed && other.transposed )
			return -1;
		else
			return 0;
	}