object identity and hashing

[Jeff Schwab]

castironpi at gmail.com wrote:
> On Feb 24, 9:28 pm, George Sakkis <george.sak... at gmail.com> wrote:
>>
>> [1]http://www.martinfowler.com/eaaCatalog/identityMap.html
> 
> [1] illustrates a case in which 'a is a' returns False, and in the
> other corner of the DeMorgan table, there is 'a is b' returns True for
> 'a == b' False.

What is the 'a is a' == False case?  I don't see anything like that 
illustrated on the Identity Map page.  Is it "P of EAA?"