Explicit calculations in an infinitesimal singular block of SL n
Let $G= SL_{n+1}$ be defined over an algebraically closed field of characteristic $p > 2$ . For each $n \geq 1$ , there exists a singular block in the category of $G_1$ -modules, which contains precisely $n+1$ irreducible modules. We are interested in the ‘lift’ of this block to the category of $...
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Veröffentlicht in: | Proceedings of the Edinburgh Mathematical Society 2022-02, Vol.65 (1), p.19-52 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Let
$G= SL_{n+1}$
be defined over an algebraically closed field of characteristic
$p > 2$
. For each
$n \geq 1$
, there exists a singular block in the category of
$G_1$
-modules, which contains precisely
$n+1$
irreducible modules. We are interested in the ‘lift’ of this block to the category of
$G_1T$
-modules. Imposing only mild assumptions on
$p$
, we will perform a number of calculations in this setting, including a complete determination of the Loewy series for the baby Verma modules and all possible extensions between the irreducible modules. In the case where
$p$
is extremely large, we will also explicitly compute the Loewy series for the indecomposable projective modules. |
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ISSN: | 0013-0915 1464-3839 |
DOI: | 10.1017/S0013091521000730 |