##
## It contains information about the schubert variety corresponding to a
## element y. The following data are given : a reduced expression of y;
## the complete list of all "critical pairs" (x,y), as defined in the
## Chevie manual (called "extremal pairs" within Coxeter), and their
## corresponding Kazhdan-Lusztig polynomials; the singular locus of
## the schubert variety; and the rational singular stratification.
##
## All group elements are represented by reduced expressions in GAP format,
## i.e. a left bracket [, followed by a comma-separated list of the
## generators in the expression in decimal notation, and a right bracket ].
## The numbering of the group generators is bourbaki numbering.
##
## The element y :
##
