|This article is about a function from ApCoCoA-1.|
Computes a list of across-the-street neighbors.
This command computes the list of across-the-street neighbors in the border of the order ideal OO. The input is a list OO of terms that specify an order ideal. The output is a list of quadruples [i,j,k,l] such that x_k * b_i = x_l * b_j where the border terms b_i and b_j correspond to the i-th and j-th element of the list returned by the command BB.Border(OO).
@param OO A list of terms representing an order ideal.
@return A list of across-the-street neighbors of OO.
Use QQ[x,y,z]; BB.Border([1,x]); BB.ASneighbors([1,x]); [z, y, xz, xy, x^2] ------------------------------- [[1, 2, 2, 3], [3, 4, 2, 3], [3, 5, 1, 3], [4, 5, 1, 2]] -- E.g. the first quadruple of the result can be interpreted -- as that y*z = z*y