Home Online Manual
Top
Back: SchurS
Forward: part
FastBack:
FastForward:
Up: chern_lib
Top: Singular Manual
Contents: Table of Contents
Index: Index
About: About this document

D.5.2.51 SchurCh

Procedure from library chern.lib (see chern_lib).

Usage:
SchurCh(I, C); I list of integers representing a partition, C list of polynomials

Return:
poly

Purpose:
computes the Schur polynomial in the Chern classes C, i.e., in the elementary symmetric polynomials, with respect to the partition I

Note:
if C are the Chern classes of the tautological bundle on a grassmanian, this gives the cohomology class of a Schubert cycle

Example:
 
LIB "chern.lib";
// The Schur polynomial corresponding to the partition 1,2,4
// and the Chern classes c(1), c(2), c(3)
ring r=0,(c(1..3)), dp;
list I=1,2,4;
list C=c(1..3);
print( SchurCh(I, C) );
==> c(1)^2*c(2)*c(3)-c(2)^2*c(3)-c(1)*c(3)^2
// Compare this with the Schur polynomial computed using Segre classes
list S=segre( chDual( list(c(1..3)) ), 6 );
print(SchurS(I,S));
==> c(1)^2*c(2)*c(3)-c(2)^2*c(3)-c(1)*c(3)^2