Hi Andrea,
f you have a simple equation to solve for one variable, its difficult to stop the process.
If its a system of equations with a set of variables, Sort[] the equation list for the Count [] of the variables and try a Reduce[] on the subset of equations for a single variable and Replace[] the Rest[] of the equation list by possible solutions found for single variables.
Such an algorithm is in some sense implemented in Groebner basis on the list of expr, in the set expr==0. It is an abstract schema like eliminating variables step by step in high school algebra.
The list of equivalent expressions to be set to zero can be used to make a run through a tree of Solve and Replace until for thr first time the complete list evaluates to zeros.
Regards Roland
