Q:

How to test whether two countries are adjacent using ArcGIS Desktop?

I have an interesting question:
Is there a dataset by which I can use to test whether two countries are adjacent? For example, if inputs are Mexico and U.S., they are adjacent; if inputs are England and Russia, they are not. Is it easy to produce an adjacency matrix for all the countries?
Edited: This question might be extended as, if we get a political boundary map, is there any ways to produce an adjacency matrix for all the political entities (e.g. Given a map of Florida, can a counties matrix be built to indicate the adjacency of all the counties)

A:

In ArcGIS 10.1 you can use the Geometry on Geometry Check Tool

and use the 'Spatial Relation Check Touches'
Touches—A part of the feature from feature class 1 comes into contact with the boundary of a feature from feature class 2. The interiors of the features do not intersect. 
http://resources.arcgis.com/en/help/main/10.1/index.html#/Finding_geometries_with_spatial_relationships/01020000001n000000/

A:

I've created an ArcGIS 10.0 Add-in that will list adjacent features of a dataset. It also allows you to show adjacent features that share the same attributes.

