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monoid(...,Degrees=>...) -- specify the degrees of the variables

Description

The Degrees option specifies the degrees of the variables in the monoid. If provided, the value must be a list or sequence with as many entries (after splicing and flattening) as there are variables. Each degree is an integers or a list of integers. Degrees provided as integers will be converted into multidegrees of length 1.

i1 : QQ[x,y,z, Degrees => {2:1, 2}]

o1 = QQ[x..z]

o1 : PolynomialRing
i2 : degrees oo

o2 = {{1}, {1}, {2}}

o2 : List
i3 : QQ[x,y, Degrees => {{1,0}, {0,1}}]

o3 = QQ[x..y]

o3 : PolynomialRing
i4 : degrees oo

o4 = {{1, 0}, {0, 1}}

o4 : List

The DegreeRank option specifies the degree length of the monoid. If provided, the value must be an integer. If the Degrees option is not provided, the degrees of the variables are determined similar to this example.

i5 : QQ[a..f, DegreeRank => 3]

o5 = QQ[a..f]

o5 : PolynomialRing
i6 : transpose matrix degrees oo

o6 = | 1 0 0 0 0 0 |
     | 0 1 0 0 0 0 |
     | 0 0 1 1 1 1 |

              3       6
o6 : Matrix ZZ  <-- ZZ

Finally, the DegreeGroup option specifies the degree group of the monoid. If provided, the value must be a $\ZZ$-module. If the Degrees option is not provided, the degrees of the variables are determined similar to the previous example.

i7 : QQ[a..f, DegreeGroup => ZZ^2 ++ coker matrix 3]
 -- Warning: computations over rings with torsion grading groups are experimental

o7 = QQ[a..f]

o7 : PolynomialRing
i8 : degreeGroup oo

o8 = cokernel | 0 |
              | 0 |
              | 3 |

                              3
o8 : ZZ-module, quotient of ZZ

This option may also be used when creating a new ring from an existing ring, creating a tensor product ring, or symmetric algebra.

See also

Functions with optional argument named Degrees:

Further information

  • Default value: null
  • Function: monoid -- make or retrieve a monoid
  • Option key: Degrees -- an optional argument

The source of this document is in Macaulay2Doc/functions/monoid-doc.m2:563:0.