That slide was a simplification of the Lambda Cube that they showed right at the end. That's probably a good starting point for better references: http://en.wik

That slide was a simplification of the Lambda Cube that they showed right at the end. That's probably a good starting point for better references: http://en.wikipedia.org/wiki/Lambda_cube http://en.wikipedia.org/wiki/Lambda_cube ... the wiki page isn't particularly approachable, but there's more detail if you follow the links.