A POLYNOMIAL INVARIANT FOR KNOTOIDS
概要
A polynomial invariant for multi-knotoids in S^2 is given by an elementary and combinatorial method. It is shown that the invariant is an extension of “a” HOMFLY polynomial for multi-knotoids and that there exist infinitely many non-trivial knotoids with trivial HOMFLY polynomial. Furthermore, formulas between the polynomials for a given multi-knotoid, its mirror and reverse images are given. By using the formulas, it is revealed that each knotoid with less than four crossings is invertible.