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flat(Arrangement,List) -- make a flat from a list of indices

Function: flat
Usage:

flat(A,L)
Inputs:
- A, a hyperplane arrangement, hyperplane arrangement
- L, a list, list of indices in flat
Optional inputs:
- Validate => a Boolean value, default value true, whether or not to check if $L$ is indeed a flat of $A$ (default true)
Outputs:
- a flat in an hyperplane arrangement, corresponding flat

Description

With the option Validate => true (which is the case by default), flat(A,L) checks to see whether $L$ is indeed the list of indices of a flat of $A$.

i1 : A = typeA 2

o1 = {x  - x , x  - x , x  - x }
       1    2   1    3   2    3

o1 : Hyperplane Arrangement

i2 : flat(A, {0,1,2})

o2 = {0, 1, 2}

o2 : Flat of {x  - x , x  - x , x  - x }
               1    2   1    3   2    3

See also

flats(ZZ,Arrangement) -- list the flats of an arrangement of a given rank
flats(Arrangement) -- list the flats of an arrangement of a given rank

Ways to use this method:

flat(Arrangement,List) -- make a flat from a list of indices

The source of this document is in HyperplaneArrangements.m2:2405:0.