PreprintCC BY 4.0HAL
COUNTING 3-LETTER SUBWORDS IN AN ASCENT SEQUENCE
Abstract
Ascent sequences have become an important object of study in enumerative combinatorics due to their rich structure and connections with several combinatorial classes. In this paper, we develop a general method to analyze the generating function that counts the total number of occurrences of a fixed 3-letter subword pattern τ in ascent sequences of length n, refined by the number of ascents. Our method provides a unified framework for studying subword pattern occurrences in these sequences. As applications of the method, we investigate in detail the cases τ = 000, 001, 011, 012, 100, 110, and 210, deriving the corresponding generating functions and highlighting structural differences between these patterns.
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BibTeX
@misc{mansour2026counting,
title = {{COUNTING 3-LETTER SUBWORDS IN AN ASCENT SEQUENCE}},
author = {Toufik Mansour},
howpublished = {HAL},
year = {2026},
month = oct,
url = {https://hal.science/hal-05833872v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - COUNTING 3-LETTER SUBWORDS IN AN ASCENT SEQUENCE
AU - Toufik Mansour
PY - 2026
DA - 2026/10/22
PB - HAL
UR - https://hal.science/hal-05833872v1
AB - Ascent sequences have become an important object of study in enumerative combinatorics due to their rich structure and connections with several combinatorial classes. In this paper, we develop a general method to analyze the generating function that counts the total number of occurrences of a fixed 3-letter subword pattern τ in ascent sequences of length n, refined by the number of ascents. Our method provides a unified framework for studying subword pattern occurrences in these sequences. As applications of the method, we investigate in detail the cases τ = 000, 001, 011, 012, 100, 110, and 210, deriving the corresponding generating functions and highlighting structural differences between these patterns.
ER -