1. propositional
   proof by cases
   modular arith
   pigeonhole
   limits of pdf

2. posets/chains

3. invariants

4. annuities and series

5. combinatorics

6. qualitative conditional prob

7. equiv relations & uniform sample space

8. conditional prob, sample space, false proof

9. propositional & Markov

10. coupon & Harmonic

11. Wald 

12. Weak Law and quantifiers

13. Markov

14. graphs, Chebyshev

15. Ruin, linear recurrence.