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Aug 20, 2018 at 17:57 comment added Ian Agol For higher dimensional varieties, one ought to be able to take valuations associated to ideal points and get actions on Bruhat-Tits buildings, and hence presentations as a complex of groups (generalizing the notion of a graph of groups). However, I don't know a reference immediately.
Aug 20, 2018 at 16:32 comment added user127776 @ulrich Thanks that was helpful but still Soule works over polynomial rings with one variable. I'm not sure but one might able to generalized his work for curves but I imagine things doesn't work well for higher dimensional varieties. In my opinion local fields seems to be an essential part of the Bruhat-Tits building which you have access to them only when you work with curves over finite fields. I suspect one might need Parshin's Bruhat-Tits buildings for higher dimensional local fields for general varieties, which looks like they are not well studied.
S Aug 20, 2018 at 13:16 history suggested Uriya First CC BY-SA 4.0
Fixed a misprint in the statement of Serre's generalization of Nagao's result: "variety" should be "curve".
Aug 20, 2018 at 9:36 comment added naf For GL_n, or more generally a Chevalley group, there is a generalisation of Nagao's theorem by C.Soule, "Chevalley groups over polynomial rings".
Aug 20, 2018 at 9:19 comment added Uri Bader Note that $\text{SL}_3(\mathbb{Z})$ and $\text{SL}_3(\mathbb{F}_p[t])$ have Serre's property FA: every action on a tree has a fixed point.
Aug 20, 2018 at 7:55 review Suggested edits
S Aug 20, 2018 at 13:16
Aug 20, 2018 at 5:25 history edited Martin Sleziak CC BY-SA 4.0
added link to the paper
Aug 20, 2018 at 4:29 history edited user127776 CC BY-SA 4.0
edited body
Aug 20, 2018 at 1:48 history asked user127776 CC BY-SA 4.0