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AN ESTIMATE OF THE UNKNOTTING NUMBERS FOR VIRTUAL KNOTS BY FORBIDDEN MOVES

MIGIWA SAKURAI

Division of Mathematics, Graduated School of Science, Tokyo Woman's Christian University, 2-6-1, Zempukuji, Suginami-ku, Tokyo 167-8585, Japan

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https://doi.org/10.1142/S0218216513500090Cited by:6 (Source: Crossref)

Abstract

It is known that any virtual knot can be deformed into the trivial knot by a finite sequence of forbidden moves. In this paper, we give the difference of the values obtained from some invariants constructed by Henrich between two virtual knots which can be transformed into each other by a single forbidden move. As a result, we obtain a lower bound of the unknotting number of a virtual knot by forbidden moves.

Keywords:

AMSC: 57M25

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