Ok thanks. Le mardi 9 juin 2015 11:52:13 UTC+2, Ralf Hemmecke a écrit : > > Hello Souleiman, > > can you stop posting HTML and not attaching irrelevant old mails? > > > In my rules for the simplification of my matrix 4*4, there a lot of > > expression of the type « *y11*y12==-y12*y11* », in fact the place of > the* > > yij *(*in the first position or in the second position, there are > commuting > > only if all the indice are different*) is important but i remark that > for > > fricas it is the same. > > FriCAS is one of the few systems that can use "*" both for denoting > commutative and non-commutative multiplication. However, within the type > Expression(Integer) "*" is meant to be commutative. > > > Here are my rules : « *yjk*yjl=-yjl*yjk for k ≠ l;ykj*ylj=-ylj*ykj for k > ≠ > > l; yjk*ylm=ylm*yjk for j ≠ l and k ≠ m*». > > OK. But I have the impression that this is only part of your problem. > Obviously, you want to have this in connection with your logrules. For a > good suggestion it would be good to have a full description of what you > are trying to achieve. > > In particular, you seem to focus on (simplification) rules. FriCAS is > different to most other CAS. One usually doesn't just enter an > expression and then "simplifies" or transforms it, but rather one thinks > in advance in which "domain" that expression lives. > > So for your "non-commutative" multiplication I would probably define a > polynomial ring with the yij's as variables and a special > multiplication. And then enter your data as elements of this domain. > Then the "simplification" happens automatically, since your "domain" > knows all about the properties of the non-commutative multiplication. In > other words, you implement a non-commutative algebra and then work in > that. > Yes, that involves a bit of programming. > > If, however, you want to use such an algebra in connection with rules, > it probably gets a little more involved. > > Ralf > >
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