CASA Function: neighborhoodTree
Checks whether a given object is a neighborhood tree.
Calling Sequence:
 b := `type/neighborhoodTree`(l)
 b := type(l,neighborhoodTree)
Parameters:
 l : list(list)

Result:
 b : boolean
 Either true or false, depending on whether the list of lists is a neighborhood tree or not.
Description:
 This function checks whether a given object is a neighborhood tree or not.
 A neighborhood tree is defined recursively. First of all, the empty list is a neighborhood tree. A list l of lists is a neighborhood tree if, first of al, the lists l[i] in l contain six elements. The first element is a nonnegative integer; the second, third and fourth elements are coordinates of a point in a projective plane. The fifth element is a set of transformations. The sixth element l[i][6] again is a neighborhood tree. And if, secondly, this definition ends; i.e. for every 1 <= i <= nops(l) we have a certain k[i] such that l[i][6][6]..[6] = [] with k[i] levels.
Examples:
> A := mkImplAlgSet([y^6x^3+x^4+x^6],[x,y]);
> G := neighbGraph(A);
> type(G,neighborhoodTree);
See Also:
[CASA]
[neighbGraph]