Discrete mathematics

Speaker: 
Anthony Lazzeroni

November 7, 2023

ZOOM
HTTPS://UBC.ZOOM.US/J/62676242229?PWD=RURTUC9UYXEWEVZTMTNGT1EVY1FLZZ09
Vancouver, BC
Canada

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Abstract: 

We introduce a new P basis for the Hopf algebra of quasisymmetric functions that refine the symmetric powersum basis. Its expansion in quasisymmetric monomial functions is given by fillings of matrices. This basis has a shuffle product, a deconcatenate coproduct, and has a change of basis rule to the quasisymmetric fundamental basis by using tuples of ribbons. The product and coproduct are then extended to matrix fillings thereby defining a Hopf algebra of matrix fillings. We lift our quasisymmetric powersum P basis to the Hopf algebra of quasisymmetric functions in non-commuting variables by introducing fillings with disjoint sets. Finally, we look at this P basis under Hivert's local action.

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