# ApCoCoA-1:BB.ASneighbors

From ApCoCoAWiki

## borderbasis.ASneighbors

compute list of across-the-street neighbors

### Syntax

$borderbasis.ASneighbors(OO:LIST):LIST

### Description

Computes the list of across-the-street neighbors in the border of the order ideal OO. The input is a list of terms OO that specifies an order ideal. The output is a list of quadruples <formula>[i,j,k,l]</formula> such that <formula>x_k * b_i = x_l * b_j</formula>.