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deletion -- deletion of subset of matroid

Usage:

deletion(M, S)

M \ S
Inputs:
- M, a matroid,
- S, a set, of indices, or a list of elements in M
Outputs:
- a matroid, the deletion M \ S

Description

The deletion M \ S is obtained by restricting to the complement of S.

i1 : M = matroid({a,b,c,d},{{a,b},{a,c}})

o1 = a "matroid" of rank 2 on 4 elements

o1 : Matroid

i2 : N = M \ {a}

o2 = a "matroid" of rank 1 on 3 elements

o2 : Matroid

i3 : peek N

o3 = Matroid{bases => {set {0}, set {1}} }
             cache => CacheTable{...1...}
             groundSet => set {0, 1, 2}
             rank => 1

i4 : N == M \ set{0}

o4 = true

See also

restriction -- restriction to subset of matroid
contraction -- contraction of subset of matroid
minor -- minor of matroid

Ways to use deletion:

deletion(Matroid,List)
deletion(Matroid,Set)

For the programmer

The object deletion is a method function.

The source of this document is in Matroids/doc-Matroids.m2:1381:0.