20. Some functions for accessing basic data
  
      |  BoundaryMap(C)  Inputs a resolution, chain complex or cochain complex C and returns the function C!.boundary.                                                                                                                                                                                                      | 
      |  BoundaryMatrix(C,n)  Inputs a chain or cochain complex C and integer n>0. It returns the n-th boundary map of C as a matrix.                                                                                                                                                                                       | 
      |  Dimension(C)   Dimension(M)  Inputs a resolution, chain complex or cochain complex C and returns the function C!.dimension . Alternatively, inputs an FpG-module M and returns its dimension as a vector space over the field of p elements.                                                                       | 
      |  EvaluateProperty(X,"name")  Inputs a component object X (such as a ZG-resolution or chain map) and a string "name" (such as "characteristic" or "type"). It searches X.property for the pair ["name",value] and returns value. If X.property does not exist, or if ["name",value] does not exist, it returns fail. | 
      |  GroupOfResolution(R)  Inputs a ZG-resolution R and returns the group G.                                                                                                                                                                                                                                            | 
      |  Length(R)  Inputs a resolution R and returns its length (i.e. the number of terms of R that HAP has computed).                                                                                                                                                                                                     | 
      |  Map(f)  Inputs a chain map, or cochain map or equivariant chain map f and returns the mapping function (as opposed to the target or the source of f) .                                                                                                                                                             | 
      |  Source(f)  Inputs a chain map, or cochain map, or equivariant chain map, or FpG-module homomorphism f and returns it source.                                                                                                                                                                                       | 
      |  Target(f)  Inputs a chain map, or cochain map, or equivariant chain map, or FpG-module homomorphism f and returns its target.                                                                                                                                                                                      |