Variable names are not arbitrary. They have meaning. Single-letter lower-case variables hardly cover all possible names. Mathematica, just like, real mathemati

Variable names are not arbitrary. They have meaning. Single-letter lower-case variables hardly cover all possible names. Mathematica, just like, real mathematics, allows you to have variable names with subscripts/superscripts/greek-letters etc. E.g. a_g is distinct from a_f (which are both rendered in rich text) My recommendation is not that everyone buy Mathematica, but that sympy figures out a way to allow every sequence of letters and numbers (that start with a letter) to automatically become a variable without declaration.