bracket/list processing

[÷ÌÁÄÉÍÉÒ òÙËÏ×]

Hello from full of snow Moscow.

In the converter I write:

======
expression :
               andorexpression
                        ;
andorexpression:
                 setexpression
               | andorexpression andor andorexpression  {
                                        }
     ;
setexpression :

               simpleexpression
             | simpleexpression setoper simpleexpression
                                        {
}
;
simpleexpression:    
                      mathexpr
                  |   mathexpr relation mathexpr
                                            {
}
;
mathexpr:
                        variable
                     |  mathexpr mathoper mathexpr
                                 {
                                 }
        ;
                                 ...
    
======
1) Every expression can be in brackets - for obvious Math reasons.

But I can not get it working.

2) I meet also the strings with lists like:

    A = {x} but also :  A = {x,y} , A = {x,y,z} and so on

3) The easiest Q - should I treat the "unary minus" exactly as standard manual 
(calc sample) tells?


Every wise words or ideas are welcome. The real samples are even better :-)

--

P bI K O B  B. B.    MOCKBA