- From: Robert Miner <rminer@geomtech.com>
- Date: Sat, 9 Oct 1999 12:45:44 -0500
- To: devlinh@nwu.edu
- CC: www-math@w3.org

Hi Hugh, > The MathML rec includes a RightArrow, implies content element, but > apparently absent is a LeftRightArrow, equivalence operator. Unless I'm > missing something? I think you're missing something. I assume you are using TeX terminology here, and are thinking of a double arrow with heads at both ends typically indicating the (logicial) equivalence "if and only if". The official unicode point for that character is 0x21D4 and its official unicode entity name is ⇔. In MathML it also has a a couple of aliases which are valid -- ⇔ and ⇔. For some reason that I don't know, the TeX name lost out here, and the obvious guess -- ↔ -- is actually a synonym for TeX's \leftrightarrow. In general, most of these naming issues came up as uncomfortable compromises. MathML has *lots* more characters (and specifically arrows) than TeX and though in general we tried very hard to stay compatible with TeX names, that wasn't always possible, especially since TeX, LaTeX, AMSTeX etc are not always consistent amongst themselves. --Robert ---------------------------------------------------------------- Robert Miner http://www.webeq.com Geometry Technologies, Inc. email: rminer@geomtech.com phone: 651-223-2884 ----------------------------------------------------------------

Received on Saturday, 9 October 1999 13:45:46 UTC