# ApCoCoA-1:BB.NDneighbors

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This article is about a function from ApCoCoA-1. |

## BB.NDneighbors

Computes a list of next-door neighbors.

### Syntax

BB.NDneighbors(OO:LIST):LIST

### Description

This command computes the list of next-door 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 triples `[i,j,k]` such that `b_i = x_k * 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 next-door neighbors of

`OO`.

#### Example

Use QQ[x,y,z]; BB.Border([1,x]); BB.NDneighbors([1,x]); [z, y, xz, xy, x^2] ------------------------------- [[3, 1, 1], [4, 2, 1]] -- E.g. the first triple of the result can be interpreted -- as x*z = xz