@ARTICLE{10.21494/ISTE.OP.2023.0939, 

TITLE={Gysin-(ℤ/2ℤ)<sup><em>d</em></sup>-functors}, 
  
AUTHOR={Dorra Bourguiba, Said Zarati, }, 
	
JOURNAL={Advances in Pure and Applied Mathematics}, 
	
VOLUME={14}, 

NUMBER={Issue 2 (Special CSMT 2022)}, 
	
YEAR={2023}, 

URL={https://www.openscience.fr/Gysin-%E2%84%A4-2%E2%84%A4-d-functors}, 
	
DOI={10.21494/ISTE.OP.2023.0939}, 
	
ISSN={1869-6090}, 
	
ABSTRACT={Let d ≥ 1 be an integer and Kd be a contravariant functor from the category of subgroups of (ℤ/2ℤ)d to the category of graded and finite &#120125;2-algebras. In this paper, we generalize the conjecture of G. Carlsson [C3], concerning free actions of (ℤ/2ℤ)d on finite CW-complexes, by suggesting, that if Kd is a Gysin-(ℤ/2ℤ)d-functor (that is to say, the functor Kd satisfies some properties, see 2.2), then we have:
$$$\big(C_{d} \big): \; \underset{i \geq 0}{\sum}dim_{\mathbb{F}_{2}} \big(\mathcal{K}_{d}(0)\big)^{i} \geq 2^{d}$$$
We prove this conjecture for 1 ≤ d ≤ 3 and we show that, in certain cases, we get an independent proof of the following
results (for d = 3 see [C4]):
If the group (ℤ/2ℤ)d, 1 ≤ d ≤ 3, acts freely and cellularly on a finite CW-complex X, then $$${\underset{i \geq 0}{\sum}}dim_{\mathbb{F}_{2}}H^{i}(X;\; \mathbb{F}_{2}) \geq 2^{d}$$$}}