ensureDGAlgebraCaches -- Guarantee that the standard cache sub-tables are present

Usage:

A = ensureDGAlgebraCaches A

M = ensureDGAlgebraCaches M
Inputs:
- A, an instance of the type DGAlgebra,
- M, an instance of the type DGModule,
Outputs:
- an instance of the type DGAlgebra or an instance of the type DGModule, The same object, with any missing standard cache sub-table created (the method mutates the input and returns it).

Description

ensureDGAlgebraCaches is idempotent: it creates the cache sub-tables that the rest of the package expects (the homology, homologyAlgebra, and diffs sub-tables for a DG algebra; the diffs sub-table for a DG module), and leaves any that already exist untouched. Code that reads from the cache can call this method once up front and thereafter assume the sub-tables are present with the right types, rather than defensively checking each access.

i1 : R = QQ[x, y] / ideal(x^2, y^2)

o1 = R

o1 : QuotientRing

i2 : A = koszulComplexDGA R

o2 = {Ring => R                          }
      Underlying algebra => R[T   ..T   ]
                               1,1   1,2
      Differential => {x, y}

o2 : DGAlgebra

i3 : ensureDGAlgebraCaches A

o3 = {Ring => R                          }
      Underlying algebra => R[T   ..T   ]
                               1,1   1,2
      Differential => {x, y}

o3 : DGAlgebra

i4 : assert(instance(A.cache, CacheTable))

i5 : ensureDGAlgebraCaches A

o5 = {Ring => R                          }
      Underlying algebra => R[T   ..T   ]
                               1,1   1,2
      Differential => {x, y}

o5 : DGAlgebra

i6 : assert(instance(A.cache, CacheTable))

i7 : KM = koszulComplexDGM R^1

o7 = {Base ring => R                    }
      DG algebra => R[T   ..T   ]
                       1,1   1,2
                                       1
      Natural module => (R[T   ..T   ])
                            1,1   1,2
      Generator degrees => {{0, 0}}
      Differentials on gens => {0}

o7 : DGModule

i8 : ensureDGAlgebraCaches KM

o8 = {Base ring => R                    }
      DG algebra => R[T   ..T   ]
                       1,1   1,2
                                       1
      Natural module => (R[T   ..T   ])
                            1,1   1,2
      Generator degrees => {{0, 0}}
      Differentials on gens => {0}

o8 : DGModule

i9 : assert(instance(KM.cache, CacheTable))

Ways to use ensureDGAlgebraCaches:

ensureDGAlgebraCaches(DGAlgebra)
ensureDGAlgebraCaches(DGModule)

For the programmer

The object ensureDGAlgebraCaches is a method function.

The source of this document is in /build/reproducible-path/macaulay2-1.26.05+ds/M2/Macaulay2/packages/DGAlgebras/doc.m2:7459:0.

ensureDGAlgebraCaches -- Guarantee that the standard cache sub-tables are present

Description

See also

Ways to use ensureDGAlgebraCaches:

For the programmer