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CellularResolutions -- A package for cellular resolutions of monomial ideals

Description

This package aims to make working with cellular resolutions of monomial ideals possible. Although the focus is on those constructs needed to work with cellular resolutions, the package additionally provides basic functions to work with cell complexes. For some direct ways to construct common cellular resolutions for monomial ideals, see taylorComplex and hullComplex.

More generally, cell complexes can be constructed by creating cells using newCell or newSimplexCell, and then the maximal cells can be provided to cellComplex to construct a cell complex

Authors

Version

This documentation describes version 1.0 of CellularResolutions.

Source code

The source code from which this documentation is derived is in the file CellularResolutions.m2. The auxiliary files accompanying it are in the directory CellularResolutions/.

Exports

  • Types
    • Cell -- the class of all cells in cell complexes
    • CellComplex -- the class of all cell complexes
  • Functions and commands
    • boundary -- returns the boundary cells along with relative orientations
    • boundaryCells -- returns the boundary cells of the given cell
    • cellComplex -- create a cell complex
    • cellComplexRPn -- gives a $RP^n$ as a cell complex
    • cellComplexSphere -- gives a sphere as a cell complex
    • cellComplexTorus -- gives a torus as a cell complex
    • cellLabel -- return the label of a cell
    • cells -- return the cells of a cell complex as a hashtable whose keys are cell dimensions
    • hullComplex -- gives the hull complex of a monomial ideal
    • isCycle -- checks if a list of cells with orientation make a cycle
    • isFree -- checks if the labels of a cell complex are free modules
    • isMinimal -- check if a labeled cell complex supports a minimal resolution
    • isSimplex -- check if a cell is a simplex
    • maxCells -- gives the maximal cells of a cell complex
    • newCell -- creates a new cell
    • newSimplexCell -- create a new cell
    • relabelCellComplex -- relabels a cell complex
    • scarfComplex -- gives the hull complex of a monomial ideal
    • subcomplex -- the subcomplex induced by a degree or monomial
    • taylorComplex -- gives the Taylor complex of a monomial ideal
  • Methods
    • boundary(Cell) -- see boundary -- returns the boundary cells along with relative orientations
    • boundaryCells(Cell) -- see boundaryCells -- returns the boundary cells of the given cell
    • boundaryMap(ZZ,CellComplex) -- compute the boundary map of a cell complex from r-faces to (r-1)-faces
    • cellComplex(Ring,List) -- see cellComplex -- create a cell complex
    • cellComplex(Ring,PolyhedralComplex) -- creates cell complex from given polyhedral complex
    • cellComplex(Ring,Polyhedron) -- creates cell complex from given polyhedron
    • cellComplex(Ring,SimplicialComplex) -- Creates a cell complex from a given simplicial complex
    • cellComplexRPn(Ring,ZZ) -- see cellComplexRPn -- gives a $RP^n$ as a cell complex
    • cellComplexSphere(Ring,ZZ) -- see cellComplexSphere -- gives a sphere as a cell complex
    • cellComplexTorus(Ring,ZZ) -- see cellComplexTorus -- gives a torus as a cell complex
    • cellLabel(Cell) -- see cellLabel -- return the label of a cell
    • cells(CellComplex) -- see cells -- return the cells of a cell complex as a hashtable whose keys are cell dimensions
    • cells(ZZ,CellComplex) -- return the cells of a cell complex
    • chainComplex(CellComplex) -- compute the cellular chain complex for a cell complex
    • dim(Cell) -- compute the dimension of a cell
    • dim(CellComplex) -- compute the dimension of a cell complex
    • facePoset(CellComplex) -- generates the face poset of a cell complex
    • HH CellComplex -- compute the homology modules of a cell complex
    • HH^ZZ CellComplex -- cohomology of a cell complex
    • HH_ZZ CellComplex -- compute the homology modules of a cell complex
    • hullComplex(MonomialIdeal) -- see hullComplex -- gives the hull complex of a monomial ideal
    • hullComplex(QQ,MonomialIdeal) -- see hullComplex -- gives the hull complex of a monomial ideal
    • hullComplex(ZZ,MonomialIdeal) -- see hullComplex -- gives the hull complex of a monomial ideal
    • isCycle(List) -- see isCycle -- checks if a list of cells with orientation make a cycle
    • isFree(CellComplex) -- see isFree -- checks if the labels of a cell complex are free modules
    • isMinimal(CellComplex) -- see isMinimal -- check if a labeled cell complex supports a minimal resolution
    • isSimplex(Cell) -- see isSimplex -- check if a cell is a simplex
    • isWellDefined(Cell) -- checks if a cell is well defined
    • isWellDefined(CellComplex) -- checks if a cell complex is well defined
    • maxCells(CellComplex) -- see maxCells -- gives the maximal cells of a cell complex
    • newCell(List) -- see newCell -- creates a new cell
    • newCell(List,Ideal) -- see newCell -- creates a new cell
    • newCell(List,Module) -- see newCell -- creates a new cell
    • newCell(List,Number) -- see newCell -- creates a new cell
    • newCell(List,RingElement) -- see newCell -- creates a new cell
    • newSimplexCell(List) -- see newSimplexCell -- create a new cell
    • newSimplexCell(List,Ideal) -- see newSimplexCell -- create a new cell
    • newSimplexCell(List,Module) -- see newSimplexCell -- create a new cell
    • newSimplexCell(List,Number) -- see newSimplexCell -- create a new cell
    • newSimplexCell(List,RingElement) -- see newSimplexCell -- create a new cell
    • relabelCellComplex(CellComplex,HashTable) -- see relabelCellComplex -- relabels a cell complex
    • ring(CellComplex) -- return the base ring of a cell complex
    • RingMap ** CellComplex -- tensors labels via a ring map
    • scarfComplex(MonomialIdeal) -- see scarfComplex -- gives the hull complex of a monomial ideal
    • skeleton(ZZ,CellComplex) -- computes the $r$-skeleton of a cell complex
    • CellComplex _ List -- see subcomplex -- the subcomplex induced by a degree or monomial
    • CellComplex _ RingElement -- see subcomplex -- the subcomplex induced by a degree or monomial
    • CellComplex _ ZZ -- see subcomplex -- the subcomplex induced by a degree or monomial
    • subcomplex(CellComplex,List) -- see subcomplex -- the subcomplex induced by a degree or monomial
    • subcomplex(CellComplex,RingElement) -- see subcomplex -- the subcomplex induced by a degree or monomial
    • subcomplex(CellComplex,ZZ) -- see subcomplex -- the subcomplex induced by a degree or monomial
    • taylorComplex(MonomialIdeal) -- see taylorComplex -- gives the Taylor complex of a monomial ideal
  • Symbols

For the programmer

The object CellularResolutions is a package.