Bi-oriented Quantum Algebras, and a Generalized Alexander Polynomial for Virtual Links
Bi-oriented Quantum Algebras, and a Generalized Alexander Polynomial for Virtual Links
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双向量子代数和虚拟链路的广义亚历山大多项式
DOI:
10.1090/conm/318/05548
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发表时间:
2001
期刊:
影响因子:
--
通讯作者:
D. Radford
中科院分区:
文献类型:
--
作者:
L. Kauffman;D. Radford
This paper discusses the construction of a generalized Alexander polynomial for virtual knots and links, and the reformulation of this invariant as a quantum link invariant. We then introduce the concept of a bi-oriented quantum algebra, which provides an algebraic context for this structure. In this paper we discuss the construction of a generalized Alexander polynomial GK(s;t) via the concept of a biquandle. Our approach leads directly to a gener- alization of the Burau representation upon which this invariant is based. We then reformulate the invariant as a quantum link invariant and as a state summation. In this context we show that the normalized quantum invariant ZK(ae;? ) satisfles a Conway skein identity and reproduces GK(s;t). These invariants are useful for the theory of virtual knots and links, for they vanish on classical knots and links. Hence the invariants studied here can be used to show that many virtual knots and links are not classical. We give such examples in Section 2. We also give an example of a virtual knot that cannot be detected by the generalized Alexander polynomial. This knot is detected by the structure of the corresponding generalized Alexander module. We conclude with a diagram due to Kishino that is knotted, but is not detected by any representation of the biquandle at the time of this writing. We conjecture that the biquandle of the Kishino diagram does detect its knottedness. In the flnal section of the paper, we formulate the concept of a bi-oriented quantum algebra. This generalizes our previous concept of oriented quantum alge- bra (6, 7) to include the necessary structures to create invariants of virtual links. The invariant ZK(ae;? ) studied in this paper flts non-trivially into this framework. Subsequent papers will study the structure and applications of bi-oriented quantum algebras.