ON A BALL IN A METRIC SPACE OF KNOTS BY DELTA MOVES
Abstract
We consider the metric space of all knots on which the distance is defined by delta moves. We show that for any two knots K1 and K2 with delta distance k and for any natural numbers ℓ and m with ℓ + m = k, the intersection of the ball of radius ℓ centered at K1 and the ball of radius m centered at K2 contains infinitely many knots. We also consider the problem whether or not the center of a given ball is unique.