Re: even elder races get tired of waiting

[Jean Louis <bugs@gnu.support>]

* 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.