Table of Contents

1. Natural Deduction of Gentzen-Type 2. The Inversion Principle 3. Normal Deductions in Classical Logic 4. Normal Deductions in Intuitionistic Logic 5. Second Order Logic 6. Modal Logic 7. Some Other Concepts of Implication Appendix A. The Calculi of Sequents Appendix B. On a set theory by Fitch Appendix C. Notes on some other variants of natural deduction Bibliographical References Index Index of Symbols