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A256492 Number of idempotents in the partial Jones monoid. 0
1, 2, 7, 24, 103, 416, 1998, 8822, 45661, 213674, 1167797, 5694690, 32445914, 163151262, 960580840, 4945645808, 29899013071, 156834641076, 968947169139 (list; graph; refs; listen; history; text; internal format)



The partial Jones monoid contains all the elements of the Motzkin monoid whose pictorial representatives are subgraphs of those in the Jones monoid. The number a(n) counts the idempotent elements in this monoid in each degree n, starting from zero. This monoid was discovered by the sequence's original author and a collaborator during work on a paper yet to appear at the time of posting.


V. F. R. Jones, The Potts model and the symmetric group, in: Subfactors: Proceedings of the Taniguchi Symposium on Operator Algebras (Kyuzeso, 1993), World Sci. Publishing, 1994, 259-267.


Table of n, a(n) for n=0..18.

Egri-Nagy Attila, Organic semigroup theory: ferns growing in the Jones/Temperley-Lieb monoid, on Computational Semigroup Theory at Wordpress, September 1, 2014.

I. Dolinka, J. East et al, Idempotent Statistics of the Motzkin and Jones Monoids, arXiv: 1507.04838 [math.CO] (2015).

J. East, Egri-Nagy A., A. R. Francis, J. D. Mitchell, Finite Diagram Semigroups: Extending the Computational Horizon, arXiv:1502.07150 [math.GR], 2015.

K. Hatch, E. Ly, E. Posner, Presentation of the Motzkin Monoid, arXiv:1301.4518 [math.RT], 2013.

K. W. Lau & D. G. FitzGerald, Ideal Structure of the Kauffman and Related Monoids, Communications in Algebra, 30:7 (2006), 2617-2629. doi:10.1080/00927870600651414

J. D. Mitchell et al., Semigroups package for GAP.


In degree at most 1, the idempotents are all partial identities, giving a(0)=1 and a(1)=2. In degree 2 ,there are 7; the four partial identities, the Temperly-Lieb cup-and-cap, and its 3 subpictures (one of which is the empty picture, which is also a partial identity, hence the overcount by 1).


Sequence in context: A150446 A150447 A150448 * A150449 A150450 A150451

Adjacent sequences: A256489 A256490 A256491 * A256493 A256494 A256495




Nick Loughlin, Mar 30 2015


a(11)-a(18) computed using the GAP package Semigroups and added by James Mitchell, May 21 2016



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Last modified February 7 02:40 EST 2023. Contains 360111 sequences. (Running on oeis4.)