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Re: Math Arrows and Harpoons


Barbara,

  in this case, not so, if i am to believe my contacts in the iso coding
  working group and the unicode technical committee.  unicode will not
  assign a code to something unless it has a clear meaning.  what they
  choose to call it in their published manual is something else again;
  that may well be descriptive of the shape rather than giving the actual
  meaning.

If you say so, then I am sure that acurately reflects the current
unicode rules but if so, then at least as far as Mathematics is
concerned the rules are just plain wrong. If you have to assign spurious
meanings to characters in order to slip this stuff past the unicode
consortium, then I suppose you have to, but you can not expect that the
symbols will then be used that way in real mathematical documents.

You accept that `A' does not mean the same thing in all natural
languages. Unicode doesn't call it `the indefinite article', it calls it
`latin capital A' (or some such name). Why then insist that in all
mathematical contexts |-> should mean `maps to' ?


Actually though I am slightly confused as when later Hans made
the (good, I think) point:

    Suppose one only uses naming by
    rendering: Then the original "maps to" |-    might be named
    "rightheadleftvertical", and |=    could be named
    "rightheaddoublestemleftvertical", or something.

You said

> here i agree.

But this type of naming scheme would explicitly avoid the need to assign
mathematical meanings to these arrows, which is why it would be a good
thing, but it seems to contradict your rule above.

Ah unless I am to interpret the above `rule' to mean that unicode will
only accept the character if it has been used, at least once, in a
published source, in which it had a definite meaning. That would be
reasonable I suppose, and would be a rule designed to stop Taco
arbitrarily rotating the arrows by fractions of a degree to fill up
an entire plane of unicode....

On the other subject Hans raised. on the angle of the arrow head on
~~> and friends. I'd agree with him that they should be the same
direction as on straight arrows. I have often needed a variant arrow with
a wavy stem, but never seen or needed one in which the heads point off
in some arbitrary angle. (I'll try to find some real printed refs for you
later)



David