Re: even elder races get tired of waiting

[Jean Louis]

* Jude DaShiell <jdashiel@panix.com> [2021-03-21 18:13]:
> Usually when this kind of question comes up it's in connection with business
> and close of business on given days.  So business open on monday to close of
> business on Friday given it's the same week would be 5 days.

Yes, when it is so practical it has clear meaning.

On my side I am using periods of time to estimate completion dates.

>From 21st to 22nd is definitely one day, but we did not say when is
begin and when is end exactly.

SELECT DATE(DATE '2021-03-21' + interval '1 days');

    date    
------------
 2021-03-22

then from this SQL result I can see that result deducted from Friday
12th for 5 days yields 7th March at 00:00 o'clock, so then I can think
that in that case Friday was not calculated, I can assume calculation
was from Friday 00:00 o'clock, it does not include full Friday.

Friday deducted for 5 days does not yield Monday, it yields Sunday
00:00 o'clock. 

SELECT '2021-03-12'::date - interval '5 days';
      ?column?       
---------------------
 2021-03-07 00:00:00

Thus computers must start from somewhere, when computer is asked how
much is Friday deducted for 5 days, the answer will be Sunday, 00:00
o'clock.

Human will say that 5 days work from Monday ends on Friday, there is
no Sunday involved.