Ask Your Question

Are subtypes of Cartan types implemented correctly?

asked 2018-11-06 09:38:28 -0600

pbelmans gravatar image

Consider the following code

CartanType("B3").subtype([2, 3]).index_set()
CartanType("B3").subtype([1, 3]).index_set()

It gives

(2, 3)
(1, 2)

in Sage 8.4. Is it wrong to expect the index set of a subtype to be the subset used in defining the subtype? From my point of view this inconsistency leads to all kinds of unexpected behaviour in the relabellings for subtypes, but maybe it is intentional?

edit retag flag offensive close merge delete

1 answer

Sort by » oldest newest most voted

answered 2018-11-08 14:46:13 -0600

FrédéricC gravatar image

It seems that currently the index set for reducible types can only be consecutive integers starting from 1.

sage: ct = CartanType("B3").subtype([1, 3])
sage: ct.index_set??

This is displayed also in the following example

sage: CartanType("A5").index_set()
(1, 2, 3, 4, 5)
sage: CartanType("A5").subtype([3,4]).index_set()
(3, 4)
sage: CartanType("A5").subtype([1,4]).index_set()
(1, 2)

So there is certainly room for improvement here.

edit flag offensive delete link more


Thanks! We'll just work around it for now, maybe I'll have a go at improving Sage in the future.

pbelmans gravatar imagepbelmans ( 2018-11-12 03:35:10 -0600 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Question Tools

1 follower


Asked: 2018-11-06 09:38:28 -0600

Seen: 77 times

Last updated: Nov 08