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reg

Castelnuovo-Mumford regularity of a module

Syntax 
reg(I: IDEAL): INT
reg(R: (Quotient)RING): INT

Description
These functions computes the Castelnuovo-Mumford regularity of an ideal. The implementation of Reg using Bermejo-Gimenez Algorithm.

Implemented by Eduardo Saenz-de-Cabezon (updated to CoCoA-5 by Anna M. Bigatti).

NOTE: this is different from RegularityIndex , the regularity of a Hilbert Function.

Example 
/**/  Use R ::= QQ[x,y,z];
/**/  I := ideal(x^3, y^2);
/**/  reg(I);
4
/**/  reg(R/I);
3
/**/  PrintRes(I);
0 --> R(-5) --> R(-2)(+)R(-3)

/**/  PrintBettiDiagram(I);
        0    1
---------------
  2:    1    -
  3:    1    -
  4:    -    1
---------------
Tot:    2    1

See Also