Timeline for Semistability of local Siegel Galois rep:

8 events

when toggle format	what		by	license	comment
Sep 22, 2016 at 15:13	vote	accept	Eins Null
Sep 22, 2016 at 15:13	comment	added	Eins Null		Thank you, David! A silly mistake on my part. Question edited. Cohomological weight is good enough for me
Sep 22, 2016 at 15:12	history	edited	Eins Null	CC BY-SA 3.0	Changed GSP to its Langlands dual
Sep 22, 2016 at 14:04	answer	added	David Loeffler		timeline score: 2
Sep 22, 2016 at 11:09	history	edited	David Loeffler	CC BY-SA 3.0	Added nt.number-theory tag
Sep 22, 2016 at 9:17	comment	added	David Loeffler		Hold on: these Galois representations don't actually exist. The Galois representation associated to an automorphic rep of $\mathrm{GSp}_{2n}$ should go into the L-group, which is $\mathrm{GSpin}_{2n+1}$. There are exceptional isomorphisms $\mathrm{GSpin}_3 \cong \mathrm{GL}_2$ and $\mathrm{GSpin}_5 \cong \mathrm{GSp}_4$; but there is no such isomorphism for $n \ge 3$.
Sep 22, 2016 at 8:17	comment	added	David Loeffler		What assumptions are you making on the weight of your Siegel form? The Galois representations are typically constructed ``directly'' when the weight is cohomological, and by p-adic approximation for small weights, and it's much harder to keep track of p-adic Hodge theoretic properties when there's a p-adic approximation process involved. Note that 2 is a small weight for $\mathrm{GSp}_4$!
Sep 22, 2016 at 1:49	history	asked	Eins Null	CC BY-SA 3.0