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### variables and indeterminates

variables (program variables)
  A program variable is a string that begins with a capital alphabetical letter followed by any numbers of alphabetical letters, digits and ``_'`. A program variable is thought of a box (a carrier) which can contain Asir objects of various types. The content is called the `value' of that variable. When an expression in a program is to be evaluated, the variable appearing in the expression is first replaced by its value and then the expression is evaluated to some value and stored in the memory. Thus, no program variable appears in objects in the internal form. All the program variables are initialized to the value 0.

      [0] X^2+X+1;
      1
      [1] X=2;
      2
      [2] X^2+X+1;
      7

indeterminates
  An indeterminate is a string that begins with a small alphabetical letter followed by any numbers of alphabetical letters, digits and ``_'`. An indeterminate is a transcendental element, so-called variable, which is used to construct polynomial rings. An indeterminate cannot have any value. No assignment is allowed to it.

      [3] X=x;
      x
      [4] X^2+X+1;
      x^2+x+1
      [5] A='Dx'*(x-1)+x*y-y;
      (y+Dx)*x-y-Dx
      [6] function foo(x,y);
      [7] B=foo(x,y)*x^2-1;
      foo(x,y)*x^2-1

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