Steenrod Lengths and a Problem of Vakil

Fuente: arXiv
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Main Author: Duc, Khanh Nguyen
Format: Preprint
Published: 2021
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_version_ 1866911377293049856
author Duc, Khanh Nguyen
author_facet Duc, Khanh Nguyen
contents We give an explicit combinatorial description of the function $f(n)$ governing the Steenrod length of real projective spaces $\mathbb{RP}^n$. This function arises in stable homotopy theory through the action of Steenrod squares on mod-$2$ cohomology and is closely related to the ghost length, which measures the minimal number of spheres required to construct a space up to homotopy. Building on the directed graphs $T_n$ introduced by Vakil to encode degree constraints for Steenrod operations, we interpret $f(n)$ as the length of the longest directed path starting at $n$. Using this framework, we resolve a question posed by Vakil by deriving concrete combinatorial formulas for $f(n)$ in terms of binary classes and a distinguished family of integers, which we call Vakil numbers.
format Preprint
id arxiv_https___arxiv_org_abs_2110_01672
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Steenrod Lengths and a Problem of Vakil
Duc, Khanh Nguyen
Representation Theory
Algebraic Topology
Combinatorics
Primary 55P42, Secondary 05C20, 55S10, 68W30
We give an explicit combinatorial description of the function $f(n)$ governing the Steenrod length of real projective spaces $\mathbb{RP}^n$. This function arises in stable homotopy theory through the action of Steenrod squares on mod-$2$ cohomology and is closely related to the ghost length, which measures the minimal number of spheres required to construct a space up to homotopy. Building on the directed graphs $T_n$ introduced by Vakil to encode degree constraints for Steenrod operations, we interpret $f(n)$ as the length of the longest directed path starting at $n$. Using this framework, we resolve a question posed by Vakil by deriving concrete combinatorial formulas for $f(n)$ in terms of binary classes and a distinguished family of integers, which we call Vakil numbers.
title Steenrod Lengths and a Problem of Vakil
topic Representation Theory
Algebraic Topology
Combinatorics
Primary 55P42, Secondary 05C20, 55S10, 68W30
url https://arxiv.org/abs/2110.01672