conventions/requirements for 'is' vs '==', 'not vs '!=', etc

[Bruno Desthuilliers]

Gabriel Genellina a écrit :
> En Mon, 19 May 2008 17:58:48 -0300, bruno.desthuilliers at gmail.com 
> <bruno.desthuilliers at gmail.com> escribió:
> 
>> On 19 mai, 22:29, Luis Zarrabeitia <ky... at uh.cu> wrote:
>> (snip)
>>> The main
>>> concept here: identity [usually] implies equality,
>>
>> I really enjoyed the "usually" disclaimer !-)
> 
> In some *rare* cases, identity does not imply equality:

Yeps. That's exactly why I enjoyed this disclaimer...

(snip nan example).