Re: [Maxima-discuss] A question about expression_with_a_certain_op[n]

[Richard F. <fa...@gm...>]

The way tellsimp  and tellsimpafter work is they put additional
simplifications on particular symbols.
(In lisp-speak, they put the additional rules as part of a program on the
property list of atoms.)
You could do something like tellsimp( a =. b , ....)  in which case the
rule would be put on the atom $=.  in the system.
But as the system points out, it won't work if you are being too coy about
what you are simplifying.
as tellsimp(vague_operator_Ill_tell_you_later(a,b,c) ....);

defrule might help, or you could just cut to the chase and write
allequal(a,b,c,d)   or perhaps list_of_equals( [a,b,c,d]).

Rjf



On Thu, Oct 2, 2025 at 8:53 AM Leo Butler <Leo...@um...> wrote:

> Hello,
>
> Aren't you over-thinking this?
>
> All you are doing is playing with a list and extracting sub-lists. I
> don't see why you need to involve the simplifier or pattern matching.
> Or even define =. as an nary operator. Why not just use `eq' as the op?
>
> Best regards,
> Leo
>
> On Thu, Oct 02 2025, Eduardo Ochs <edu...@gm...> wrote:
>
> > Hi list,
> >
> > is is possible to use tellsimpafter to define the action of [n] on
> > objects of the form expression_with_a_certain_op[n]? In case of "no",
> > what is the workaround? Here's what I was trying... I defined an n-ary
> > equality operator, "=.", and I was playing with ways of extracting the
> > subexpressions and sub-equalities of objects like "a=.b=.c=.d=.e":
> >
> >   has_op_1(e)   := if not atom(e) then not subvarp(e);
> >   has_op_2(e,o) := if has_op_1(e) then is(op(e)=o);
> >   eqdotp  (e)   := has_op_2(e,"=.");
> >   matchdeclare  (_eqdot,eqdotp);
> >   matchdeclare  ([_a,_b,_n],all);
> >   matchdeclare  (_n,all);
> >   tellsimpafter (subexpr(_eqdot,_n), args(_eqdot)[_n]);
> >   nary("=.");
> >   eqdot_subexpr(e,n) := args(e)[n];
> >   eqdot_subeq  (e,n) := args(e)[n] = args(e)[n+1];
> >
> >   oo : a=.b=.c=.d=.e;
> >   [op(oo), args(oo)];    /* [=., [a, b, c, d, e]] */
> >   eqdot_subexpr(oo,2);   /* b */
> >   eqdot_subexpr(oo,3);   /* c */
> >   eqdot_subeq  (oo,2);   /* b = c */
> >   subexpr      (oo,2);   /* b */
> >
> >   tellsimpafter (_eqdot[_n], args(_eqdot)[_n]);  /* error */
> >
> > The error is:
> >
> >   tellsimpafter: main operator of pattern must not be match variable;
> >   found: _eqdot
> >
> > Thanks in advance!
> >   Eduardo Ochs
> >   https://anggtwu.net/eev-maxima.html
> >
> > _______________________________________________
> > Maxima-discuss mailing list
> > Max...@li...
> > https://lists.sourceforge.net/lists/listinfo/maxima-discuss
> >
>
> --
> ---
> Best regards,
> Dr Butler
>
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