Simple roots from weights in type A

asked 2021-10-25 12:20:33 +0100

Maxim Smirnov gravatar image

Hi everyone,

I ran into the following strange issue. Running

for a in RootSystem('A3').root_lattice().simple_roots():

gives the expected formulas for the simple roots in type A.

However, if you run instead

for a in RootSystem('A3').weight_lattice().simple_roots():

then the last root looks like


which differs from the first output by the "determinant weight" (1,1,1,1).

Anyone came across this before? This behaviour can easily cause some trouble...

Best, Maxim

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