isWeylStandard -- test whether a WeylFilling is Weyl-semistandard

• Usage:

  isWeylStandard T

• Inputs:
  • T, an instance of the type WeylFilling, assumed to have rows in sorted (weakly-increasing) order, for example the output of weylNormalize
• Outputs:
  • null if T is Weyl-standard (columns strictly increasing top-to-bottom), otherwise a pair (i, j) giving the first column violation: T#i#j >= T#(i+1)#j, scanning rows from bottom to top

i1 : isWeylStandard weyl {{0,1}, {1,2}}

i2 : isWeylStandard weyl {{1,2}, {1,3}}   -- column 0: 1 >= 1 violates

o2 = (0, 0)

o2 : Sequence