1.S>(R&~T)
2.(S&R)>(TvE)
3.(Qv~T)>~E /~S
|4. ~~S Assumption for indirect proof
|5. S 4, double negation
|6. R&~T 1,5, modus ponens
|7. R 6, simplification
|8. ~T&R 6, commutativity
|9. ~T 8, simplification
|10. S&R 5,6, conjunction
|11. TvE 2,10, modus ponens
|12. E 11,9, disjunctive syllogism
|13. ~~E 12, double negation
|14. ~(Qv~T) 3,13 modus tollens
|15. ~Q&~~T 14, deMorgan's law
|16. ~Q&T 15, double negation
|17. T&~Q 16, commutation
|18. T 17, simplification
|19. T&~T 18,9, conjunction
20. ~S lines 4-19 indirect proof
Edwin
