An ¥-unknotting (unlinking) operation is defined by S. Jablan (1998) . Every self-crossing point of a KL can be turned into an uncrossing by introducing a "mirror". This can be repeated until we obtain the unknot (link without self-crossings). Analogously as we defined unknotting (unlinking) number, it is possible to define an ¥-unknotting (unlinking) number u¥ (K) by the "classical" and "standard" definition, to prove that two definitions are equivalent, and make a Conjecture on u¥ number:
Every ¥-change transforms an alternating knot to an alternating knot, so the set of all alternating knots is closed with regard to ¥-changes. According to Tait's Flyping Theorem, all minimal projections of an alternating knot give the same result, so for every alternating knot it is sufficient to use only one minimal projection.
Again, a particular value of the u¥ number is a characteristic of a family : for the knot family (2k+1), (k ³ 1), u¥ ((2k+1)) = 1; for the knot family (2k) 2, (k ³ 1), u¥ ((2k) 2) = 2; for the knot family ((2k) (2l)), (k,l > 1), u¥ ((2k) (2l)) = 3, etc.