D Recurrences

[Timon Gehr]

Andrei Mitrovic wrote:
> On 6/9/11, Steven Schveighoffer <schveiguy at yahoo.com> wrote:
>> On Thu, 09 Jun 2011 14:45:49 -0400, Andrej Mitrovic
>> <andrej.mitrovich at gmail.com> wrote:
>>
>>> I never understood why it's called "open" interval. What does it 'open'?
>>>
>> Look at the terminology section of
>> http://en.wikipedia.org/wiki/Interval_(mathematics)
>>
>> No clue as to the "why" :)
>>
>> -Steve
>>
>
> The why is what I'm after.
>
> Let me take a look at some definitions of "open" from
> thefreedictionary (excluding the definitions under the math section):
> "Carried on in full view"
> "Spread out; unfolded"
> "Accessible to all"
> "Lacking effective regulation"
>
> It seems more natural to me to think of open as something that
> encompasses a larger scope. E.g. when you spread your arms you have a
> larger area between your hands, not smaller.

I think it is called open, because you can go into any direction from a point
within an open set without leaving the set. There are no boundaries.


Timon