Re: More /.{I->-1} craziness

*To*: mathgroup at smc.vnet.net*Subject*: [mg106168] Re: More /.{I->-1} craziness*From*: R Fateman <fateman at cs.berkeley.edu>*Date*: Sun, 3 Jan 2010 03:43:42 -0500 (EST)*References*: <200912300915.EAA17299@smc.vnet.net> <hhhmn8$o9t$1@smc.vnet.net> <201001011039.FAA05484@smc.vnet.net> <34c814851001011444x7674b2fav61b71add43515a28@mail.gmail.com>

Leonid Shifrin wrote: > Regarding this issue, I think I entirely agree with what David Bailey > and other people said: I don't consider replacement rules as a > mathematical tool for end users, but rather as an inner layer of > Mathematica, which is also exposed for flexibility / convenience and > intended primarily to be used by the more advanced users. Unfortunately many users or potential users are not as sophisticated in their understanding of the distinction between the underlying mechanisms of a syntax-driven transformation system. They simply take the marketing blurbs about "A system for doing mathematics" as a description suggesting that --hey, I do mathematics too. They don't really know what "syntax" means and they don't think they need to know, because syntax is not part of their mathematics education. Now a person educated as a computer scientist would generally know a fair amount about syntax, and might be willing to use "A system that uses syntax-directed transformation rules for computation". In fact there are several such systems that have been designed, starting in the early 1960s. In deference to Steve C's reluctance to allow the names of other computer systems to appear in mathgroup, I won't name them. But at least 6 come to my mind. I still don't understand the reluctance of people to say "OK, mathematician-who-doesn't-know syntax" ... HERE's the substitution facility for YOU. and write the program. Or at least a first cut of one, so that it can be refined. In this way, they can implement some missing functionality themselves at their own risk without the need to wait for a new Mathematica release. It is stated in the documentation that rule substitution is purely syntax-based, and therefore not guaranteed to always make sense. It says that it won't always make sense? Hm. (I am traveling and don't have Mathematica with me, and can't check...) Doesn't make sense?! How could that be.. It must make sense to SOME people. Maybe even me or you. So now there are more levels. The high-priest, keeper of the mysterium(us?). The second level priest who understands syntax but for whom some transformations "don't make sense",a person who not a true syntax-geek. Perhaps this is the typical programmer who learns some Mathematica.... The third level, maybe a skilled mathematician? The fourth level, some novice, unsophisticated student learning math; and maybe down the ladder further ? RJF

**References**:**Re: More /.{I->-1} craziness***From:*Richard Fateman <fateman@cs.berkeley.edu>