truncate(ZZ,Matroid) -- the truncation of a matroid with respect to a flat

Synopsis

• Function: truncate

• Usage:

  truncate(i, M)

• Inputs:
  • i, an integer, a non-negative integer
  • M, a matroid
• Outputs:
  • a matroid, the i-fold truncation of the matroid

Description

This function is provided by the package Matroids.

Constructs the i-fold truncation T^i(M) of the matroid M.

i1 : M = matroid completeGraph 5

o1 = a "matroid" of rank 4 on 10 elements

o1 : Matroid

i2 : T2M = truncate(2, M)

o2 = a "matroid" of rank 2 on 10 elements

o2 : Matroid

i3 : partition(F -> rank(T2M, F), flats T2M)

o3 = HashTable{0 => {set {}}                                                                                  }
               1 => {set {9}, set {8}, set {7}, set {6}, set {5}, set {4}, set {3}, set {2}, set {1}, set {0}}
               2 => {set {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}}

o3 : HashTable

See also

• elementaryQuotient -- associated to a modular cut or linear subclass
• modularCut -- associated to an elementary quotient or linear subclass
• truncate(Matroid) -- the truncation of a matroid with respect to a flat