[Xy-pic] new arrow types
Ross Moore
ross@ics.mq.edu.au
Wed, 13 Mar 2002 18:55:03 +1100 (EST)
> Hello everybody,
>
> I'd like to have an xy-pic arrow looking like \subset.
>
> (
> My expirience:
> I've tried
> \ar@{*{\subset}}
If you want an extended "contains in" arrow, as frequently used
for an injective map in abstract algebra, algebraic geometry or
category theory (and elsewhere), then:
Try this: it should work: \ar@{(->}
It uses \dir{(} as the tail , \dir{-} to build the stem
and \dir{>} for the arrowhead.
If you don't want arrow-tips, then \ar@{(-} should do it.
However, if you want a stem constructed from \subset pieces,
then one way to do it is:
\ar@{{}*{\subset}{}}
^^ ^^^^ ^^
1 2 3
In general, to make customised arrows, you need to specify
3 directional pieces.
If you give only 1 or 2 pieces, then Xy-pic tries to guess
which parts you are changing; shaft, tip or tail.
e.g. \ar@{>} is the same as \ar{->} and \ar{{}->}
(i.e. only the head is affected, similarly with \ar@{(} )
but \ar{.} alters only the stem.
This is because it's much more common to want a dotted stem
than to have a dot as the arrow-head.
If you use a "non-standard" directional; that is,
something for which \dir{<piece>} is not defined,
then you need to specify it as *{<piece>}
(This explains the *{\subset} above.)
> i.e.
> \xymatrix
> {
> A \ar@{*{\subset}}[r] & B \\
> }
> it does not look right; and I think that XY-Pic is
> right, becasue, according to
> the Users's guide, I've described the head and not
> the shaft.
> I've also tried
> \ar@{{}*{\subset}{}}
> meaning an empty tail, shaft like \subset and an
> empty head;
> it also did not work, this time I do not know
> why.
In what way did this not work ?
You should get multiple copies of \subset, stretching between
the objects at either end -- that's certainly what I get.
The pieces will *not* be rotated to match the direction of
the arrow, but will always be horizontal.
However, \ar@{{}{(}{}} will use circular arcs, rotated appropriately,
since \dir{(} is defined as an Xy-pic directional object.
> )
>
> What is the right answer? Thank you, Maxim Leenson.
>
Hope this helps,
Ross Moore
>
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