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On the negative-one shift functor for FI-modules. (English) Zbl 1359.18001

The author neatly points out how several recent concepts in the theory of FI-modules, namely the shift functor \(S\), the derivative functor \(D\), and the coinduction construction \(V\mapsto QV\), are related by simple category theoretic ties. The author first recalls a construction \(F\mapsto F^\dagger\), for a functor \(F: \text{C-Mod}\to \text{C'-Mod}\), which, if \(F\) is right exact and preserves direct sums, yields a right adjoint. This result is then applied to exhibit the negative-one shift functor as giving rise to the shift functor, the derivative functor, and the coinduction construction as, respectively, its right adjoint, left adjoint, and extension by it.

MSC:

18A40 Adjoint functors (universal constructions, reflective subcategories, Kan extensions, etc.)

References:

[1] Church, T.; Ellenberg, J., Homology of FI-modules · Zbl 1371.18012
[2] Church, T.; Ellenberg, J.; Farb, B.; Nagpal, R., FI-modules over Noetherian rings, Geom. Topol., 18, 5, 2951-2984 (2014) · Zbl 1344.20016
[3] Gan, W. L.; Li, L., Coinduction functor in representation stability theory, J. Lond. Math. Soc. (2), 92, 3, 689-711 (2015) · Zbl 1358.18001
[4] Gan, W. L., A long exact sequence for homology of FI-modules · Zbl 1358.18006
[5] Li, L., Upper bounds of homological invariants of \(FI_G\)-modules, Arch. Math. (Basel), 107, 3, 201-211 (2016) · Zbl 1395.16003
[6] Li, L.; Ramos, E., Depth and the Local Cohomology of \(FI_G\)-modules
[7] Li, L.; Yu, N., Filtrations and Homological degrees of FI-modules · Zbl 1371.13015
[8] Palmquist, J. F.; Newell, D., Bifunctors and adjoint pairs, Trans. Am. Math. Soc., 155, 293-303 (1971) · Zbl 0234.18001
[9] Ramos, E., Homological Invariants of FI-modules and \(FI_G\)-modules
[10] Rotman, J., An Introduction to Homological Algebra, Universitext (2009), Springer: Springer New York · Zbl 1157.18001
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