## Upside-down Omega; Extendable arrows

Users are invited to suggest new symbols to be included in the MathTime Professional fonts.

Cayley
Posts: 5
Joined: Sat Dec 25, 2010 9:46 pm

### Upside-down Omega; Extendable arrows

I need two things.

1. I need an upside-down capital omega, in straight and in slant. This symbol is standard in group theory, where
\UpsideDownOmega_i (P) is the subgroup of a p-group P consisting of the p^i th powers of its elements. to justify its widespread usage, I need only quote Huppert's "Endliche Gruppen", which is the classic bible of finite group theory.

2. I need extendable up, down, left, right, NE, NW, SE, SW arrows for drawing commutative diagrams of reasonable size where I can fit in symbols on the various arrows. I have done a poor job trying to fit together pieces of arrows and extension bits, but the joins never work properly, and keep shifting. Also, because I am using the symbols at 18pt, they are too thick.

Surely PCTeX can write robust macros for these eight objects, along the lines of the extendable brackets macros that work so well. Then we can use \halign for the commutative diagrams without having to go to either imported diagrams or one of the extremely complicated diagram packages.
Cayley
Posts: 5
Joined: Sat Dec 25, 2010 9:46 pm

3. I also need the four harpoon arrows to be extendable, that is,
\leftrightharpoons, \rightleftharpoons,
\updownharpoons, \downupharpoons.
I expect that that others will want extendable versions of various other arrows. There should be a generic command that extends by a given amount single arrows and double arrows. Such a command could then be applied to a range of arrow types.