Re: Why is NonCommutativeMultiply Protected?
- To: mathgroup at smc.vnet.net
- Subject: [mg82694] Re: Why is NonCommutativeMultiply Protected?
- From: "Michael Weyrauch" <michael.weyrauch at gmx.de>
- Date: Mon, 29 Oct 2007 05:28:44 -0500 (EST)
- References: <firstname.lastname@example.org>
As far as I can see there is absolutely no problem to unprotect and redefine NonCommutativeMultiply. I do it all the time in my programs. Of course, alternatively you can use e.g. Wedge and give it the attributes and properties you need. Michael "Szabolcs Horvát" <szhorvat at gmail.com> schrieb im Newsbeitrag news:fg1ivs$k16$1 at smc.vnet.net... > Why is NonCommutativeMultiply Protected? > > Is it safe to redefine NonCommutativeMultiply? Does it have any special > built-in properties (apart from being Flat and OneIdentity)? Is it used > by any of the built-in functions? > > NonCommutativeMultiply certainly does not evaluate to anything, but the > same can be said about Rule, which is not at all safe to redefine > because: 1. It has some special properties (it affects scoping, it does > not like Unevaluated, etc.) 2. It is used together with functions > such as Replace, and (most probably) built-in functions use it internally. > > So is it safe to Unprotect[NonCommutativeMultiply] and attach > definitions to it? (I know that in certain situations one can use > UpValues, but I would like to know the answer to this question.) > > -- > Szabolcs >