"The book contains an excellent combination of values: noble subject, fresh key results, and the gentle, friendly style of the author. It can be recommended as a textbook, as a handbook, or simply as high quality reading in logic." Sergei N. Artemov, Journal of Symbolic Logic

• 1. GL and other systems of propositional modal logic; 2. Peano arithmetic; 3. The box as Bew(x); 4. Semantics for GL and other modal logics; 5. Completeness and decidability of GL and K, K4, T, B, S4, and S5; 6. Canonical models; 7. On GL; 8. The fixed point theorem; 9. The arithmetical completeness theorems for GL and GLS; 10. Trees for GL; 11. An incomplete system of modal logic; 12. An S4 -preserving proof-theoretical treatment of modality; 13. Modal logic within set theory; 14. Modal logic within analysis; 15. The joint provability logic of consistency and w-consistency; 16. On GLB: the fixed point theorem, letterless sentences, and analysis; 18. Quantified provability logic with one one-place predicate letter; Notes; Bibliography; Index.

"The book contains an excellent combination of values: noble subject, fresh key results, and the gentle, friendly style of the author. It can be recommended as a textbook, as a handbook, or simply as high quality reading in logic." Sergei N. Artemov, Journal of Symbolic Logic

• 1. GL and other systems of propositional modal logic; 2. Peano arithmetic; 3. The box as Bew(x); 4. Semantics for GL and other modal logics; 5. Completeness and decidability of GL and K, K4, T, B, S4, and S5; 6. Canonical models; 7. On GL; 8. The fixed point theorem; 9. The arithmetical completeness theorems for GL and GLS; 10. Trees for GL; 11. An incomplete system of modal logic; 12. An S4 -preserving proof-theoretical treatment of modality; 13. Modal logic within set theory; 14. Modal logic within analysis; 15. The joint provability logic of consistency and w-consistency; 16. On GLB: the fixed point theorem, letterless sentences, and analysis; 18. Quantified provability logic with one one-place predicate letter; Notes; Bibliography; Index.

"The book contains an excellent combination of values: noble subject, fresh key results, and the gentle, friendly style of the author. It can be recommended as a textbook, as a handbook, or simply as high quality reading in logic." Sergei N. Artemov, Journal of Symbolic Logic

• 1. GL and other systems of propositional modal logic; 2. Peano arithmetic; 3. The box as Bew(x); 4. Semantics for GL and other modal logics; 5. Completeness and decidability of GL and K, K4, T, B, S4, and S5; 6. Canonical models; 7. On GL; 8. The fixed point theorem; 9. The arithmetical completeness theorems for GL and GLS; 10. Trees for GL; 11. An incomplete system of modal logic; 12. An S4 -preserving proof-theoretical treatment of modality; 13. Modal logic within set theory; 14. Modal logic within analysis; 15. The joint provability logic of consistency and w-consistency; 16. On GLB: the fixed point theorem, letterless sentences, and analysis; 18. Quantified provability logic with one one-place predicate letter; Notes; Bibliography; Index.