why () is () and [] is [] work in other way?

[rusi]

On Apr 24, 4:06 pm, Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-
a470-7603bd3aa... at spamschutz.glglgl.de> wrote:
> Am 24.04.2012 08:02 schrieb rusi:
>
> > On Apr 23, 9:34 am, Steven D'Aprano<steve
> > +comp.lang.pyt... at pearwood.info>  wrote:
>
> >> "is" is never ill-defined. "is" always, without exception, returns True
> >> if the two operands are the same object, and False if they are not. This
> >> is literally the simplest operator in Python.
>
> > Circular definition: In case you did not notice, 'is' and 'are' are
> > (or is it is?) the same verb.
>
> Steven's definition tries not to define the "verb" "is", but it defines
> the meanung of the *operator* 'is'.
>
> He says that 'a is b' iff a and be are *the same objects*. We don't need
> to define the verb "to be", but the target of the definition is the
> entity "object" and its identity.

Identity, sameness, equality and the verb to be are all about the same
concept(s) and their definitions are *intrinsically* circular; see
http://plato.stanford.edu/entries/identity/#2

And the seeming simplicity of the circular definitions hide the actual
complexity of 'to be'
for python:  http://docs.python.org/reference/expressions.html#id26
(footnote 7)
for math/philosophy: http://www.math.harvard.edu/~mazur/preprints/when_is_one.pdf