Shift Invariance

[Lev Goldfarb]

I would like to make one more comment. Shift invariance should be properly
thought of as invariance of a "final" object representation wrt
TRANSLATIONS of the object (to use the term from linear algebra). This is
not to be confused with the fact that the POSITION of the object is also
encoded separately, when necessary. The latter has to do with the need to 
represent the entire "scene". 

-- Lev