overlaps( a, b )
overlaps( geomFromWKT( 'LINESTRING(3 5 , 4 4 , 5 5 , 5 3)' ) , geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' )) → returns 1
overlaps( geomFromWKT( 'LINESTRING(0 0 , 1 1)' ) , geomFromWKT( 'LINESTRING(3 3 , 4 4 , 5 5)' )) → returns 0