1. From the Editors

   • Heinrich Wansing
   • Sergei Odintsov
   • Yaroslav Shramko

   EditorialNotes Pages: 153 - 157

2. A Non-deterministic View on Non-classical Negations

   • Arnon Avron

   OriginalPaper Pages: 159 - 194

3. Double-Negation Elimination in Some Propositional Logics

   • Michael Beeson
   • Robert Veroff
   • Larry Wos

   OriginalPaper Pages: 195 - 234

4. Negation in the Context of Gaggle Theory

   • J. Michael Dunn
   • Chunlai Zhou

   OriginalPaper Pages: 235 - 264

5. Gentzen-Type Methods for Bilattice Negation

   • Norihiro Kamide

   OriginalPaper Pages: 265 - 289

6. The Class of Extensions of Nelson's Paraconsistent Logic

   • Sergei P. Odintsov

   OriginalPaper Pages: 291 - 320

7. A First Order Nonmonotonic Extension of Constructive Logic

   • David Pearce
   • Agustín Valverde

   OriginalPaper Pages: 321 - 346

8. Dual Intuitionistic Logic and a Variety of Negations: The Logic of Scientific Research

   • Yaroslav Shramko

   OriginalPaper Pages: 347 - 367

9. Contracting Intuitionistic Theories

   • Neil Tennant

   OriginalPaper Pages: 369 - 391

10. Nelson's Negation on the Base of Weaker Versions of Intuitionistic Negation

    • Dimiter Vakarelov

    OriginalPaper Pages: 393 - 430

11. Socratic Proofs and Paraconsistency: A Case Study

    • Andrzej Wiśniewski
    • Guido Vanackere
    • Dorota Leszczyńska

    OriginalPaper Pages: 431 - 466

12. Contents of Volume 80

    • Editorial Board

    OriginalPaper Pages: 467 - 468