I am wondering what other decidable theorem or results that is not weaker or stronger than Tarski's theorem.


Could any one give reference or a simple introduction about such result known in their domain? 



Decidable theorem or result that is not weaker than Tarski's theorem
[Ax and Kochen](http://www.jstor.org/stable/1970476) proved decidability for the ring of $p$-adic numbers, and many rings like it. That certainly doesn't follow from Tarski, and I would say it is more difficult.


