# Quomodocumque on F_un (Update 10-21)

Posted by on Oct 14, 2008 in newsNo comments

Quomodocumque has an interesting post on F_un, buildings, the braid group and , starting from the Kapranov-Smirnov observation that should be considered as the braid group on n-strings (see also this post).

So then, what is ? For it turns out that one can use Serre’s-tree results in the description of to postulate that

, the amalgamated free product of two copies over over the common subgroup .

For higher the work of Lisa Carbone suggest the following answer :

is something like the mapping class group of a disc with n boundary components instead of n punctures.”

UPDATE tuesday october 20th

In a follow-up post, F_un and the braid group – a note of skepticism, arguments are collected against the claim that the d-string braid group should be . One of the arguments being that is a subgroup of whereas cannot be embedded into .

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