arXiv subjects

Sascha G. Lukac

Publications and source records attributed to Sascha G. Lukac.

2 recordsLinked to original sources

arXiv2001

Idempotents of the Hecke algebra become Schur functions in the skein of the annulus

The Hecke algebra H_n contains well known idempotents E_λ which are indexed by Young diagrams with n cells. They were originally described by Gyoja. A skein theoretical description of E_λ was given by Aiston and Morton. The closure of E_λ becomes an element Q_λ of the skein of the annulus. In this skein, they are known to obey the same multiplication rule as the symmetric Schur functions s_λ. But previous proofs of this fact used results about quantum groups which were far beyond the scope of skein theory. Our elementary proof uses only skein theory and basic algebra.

math.GT↗

arXiv2001

The Homfly polynomial of the decorated Hopf link

The main goal is to find the Homfly polynomial of a link formed by decorating each component of the Hopf link with the closure of a directly oriented tangle. Such decorations are spanned in the Homfly skein of the annulus by elements Q_λ, depending on partitions λ. We show how to find the 2-variable Homfly invariant <λ,μ> of the Hopf link arising from decorations Q_λand Q_μin terms of the Schur symmetric function s_μof an explicit power series depending on λ. We show also that the quantum invariant of the Hopf link coloured by irreducible sl(N)_q modules V_λand V_μ, which is a 1-variable specialisation of <λ,μ>, can be expressed in terms of an N x N minor of the Vandermonde matrix (q^{ij}).

math.GT↗