"Who cares if you are sometimes off by one year because the year 0 is
missing?". The time from the beginning of the first century BC to the beginning
of the first century AD is one century, while 1-_1=2. Who cares if you are
sometimes off by one century because the century 0 is missing? I do. Thanks!
Bo.
Den 23:54 søndag den 20. maj 2018 skrev Jose Mario Quintana
<[email protected]>:
Historians refer to specific years, using a well-known event as an anchor,
naturally as AD 1, AD 2, AD 3, ... and, going backward, as 1 BC, 2 BC, 3
BC, ...
Dropping the AD and inserting a - (_ in J) instead of BC allows for a
simple general consistent rule for calculating the years elapsed between
two dates by subtracting the lower date from the higher date; for example,
the years elapsed between (say, the beginning of) the year _4 and (the
beginning of) the year 30 can be calculated by 30 - _4 ...
Nevermind, who cares if you are sometimes off by one year because the year
0 is missing? Presumably, some people who like to date celestial events
precisely :
Astronomical year numbering
https://en.wikipedia.org/wiki/Astronomical_year_numbering
PS. There has been some debate about the exact year when the actual
aforementioned event happened: 4 BC, 1 BC, AD 1, ...
On Sat, May 19, 2018 at 9:38 AM, 'Bo Jacoby' via Chat <[email protected]>
wrote:
> The terms "ordinal number" and "cardinal number" has advanced mathematical
> meanings in the theory of infinite sets and transfinite numbers, but the
> words also have ancient meanings in grammar. The semantics of a cardinal
> number is to count the elements of a finite set, and the semantics of an
> ordinal number is to identify a single element. This century is the
> twentyfirst century. That is a 1-origin ordinal number. The number of whole
> centuries that have passed so far is 20. That is a 0-origin cardinal
> number. /Bo.
>
> Den 12:49 lørdag den 19. maj 2018 skrev R.E. Boss <
> [email protected]>:
>
>
> > A solution to the problem is to distinguish between the ordinal numbers
> (first,
> > second, and so on) and cardinal numbers (zero, one, and so on). The first
> > ordinal number is "first", and the first cardinal number is "zero".
> Cardinal
> > number are for indexing, not for counting. Thanks. Bo.
>
>
> I like that very much, although I read different things in
> https://www.wikiwand.com/en/Ordinal_number
> "A natural number (which, in this context, includes the number 0) can be
> used for two purposes: to describe the size of a set, or to describe the
> position of an element in a sequence."
> (...)
> " Whereas the notion of cardinal number is associated with a set with no
> particular structure on it, the ordinals are intimately linked with the
> special kind of sets that are called well-ordered (...) "
> (...)
> " Ordinals may be used to label the elements of any given well-ordered set
> (the smallest element being labelled 0, the one after that 1, the next one
> 2, "and so on") and to measure the "length" of the whole set by the least
> ordinal that is not a label for an element of the set."
> See also https://www.wikiwand.com/en/Cardinal_number .
>
>
> R.E. Boss
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