Twisted quandle homology theory and cocycle knot invariants

The quandle homology theory is generalized to the case when the coefficient groups admit the structure of Alexander quandles, by including an action of the infinite cyclic group in the boundary operator. Theories of Alexander extensions of quandles in relation to low dimensional cocycles are developed in parallel to group extension theories for group cocycles. Explicit formulas for cocycles corresponding to extensions are given, and used to prove non-triviality of cohomology groups for some quandles. The corresponding generalization of the quandle cocycle knot invariants is given, by using the Alexander numbering of regions in the definition of state-sums. The invariants are used to derive information on twisted cohomology groups.

Keywords

quandle homology, cohomology extensions, dihedral quandles, Alexander numberings, cocycle knot invariants

Mathematical Subject Classification 2000

Primary: 57N27, 57N99

Secondary: 57M25, 57Q45, 57T99

References

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Publication

Received: 27 September 2001

Accepted: 8 February 2002

Published: 14 February 2002

Authors

J Scott Carter
University of South Alabama Mobile AL 36688 USA

Mohamed Elhamdadi
University of South Florida Tampa FL 33620 USA

Masahico Saito
University of South Florida Tampa FL 33620 USA

Volume 2, issue 1 (2002)

J Scott Carter, Mohamed Elhamdadi and Masahico Saito