Of course, you could use an expression such as (- - ~:&*) if you like...
But, yeah, that convention does seem to be slightly... different from straight - Thanks, -- Raul On Sun, May 20, 2018 at 5:54 PM, Jose Mario Quintana <[email protected]> wrote: > 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 >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm >> >> >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm >> > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
