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Reg

Castelnuovo-Mumford regularity of a module
Syntax

Reg(M:Ideal or TAGGED("Quotient")):INT


Description
This function computes the Castelnuovo-Mumford regularity of a module.

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);
  Res(I);
0 --> R(-5) --> R(-2)(+)R(-3)
-------------------------------
  BettiDiagram(I);
        0    1
---------------
 2:     1    -
 3:     1    -
 4:     -    1
---------------
Tot:    2    1
-------------------------------
  Reg(I);
4
-------------------------------
  Reg(R/I);
3
-------------------------------


See Also