G. Bergman. (2016)cite arxiv:1602.00034Comment: Comments: 50 pages. Main change from version 2: Lemma 26 strengthened to include contractibility statement which in previous version was noted as "likely" in paragraph following that result. Several small typoes also corrected.
A. Lazar, and M. Wachs. (2018)cite arxiv:1811.06882Comment: 12 pages, 4 figures. An extended abstract, accepted to conference proceedings of Formal Power Series and Algebraic Combinatorics (FPSAC), 2019. (V2): Improvements of some results, and minor corrections. (V3): Addition of Theorem 4.5, addition of two references, and minor edits.