1.  Project:  The Axiom AC in HPL

2.  Project:  A BSS-RAM Model for Abstract Computation

Gaßner: Gelöste und offene P-NP-Probleme über verschiedenen Strukturen (Solved and open P versus NP problems over various structures, habilitation thesis, 2011)

Gaßner: Das Auswahlaxiom im Prädikatenkalkül zweiter Stufe (The Axiom of Choice in the Second-Order Logic, Dissertation, 1984, pdf)

Gaßner: Die Medialarithmetik und der mediale Körper (Medial arithmetic and the medial field, diploma thesis, 1981)

Gaßner, A. Pauly und F. Steinberg: Computing Measure as a Primitive Operation in Real Number Computation,  LIPICS Vol. 183. Online. DOI: 10.4230/LIPIcs.CSL.2021.22

Gaßner: An Introduction to a Model of Abstract Computation, in: Adrian Rezus (ed.), Contemporary Logic and Computing, College Publications, London (2020) [Landscapes in Logic 1], pp. 574–603. (Preprint 1/2019, Landscapes in Logic  Series edited by Ali Sadegh Daghighi, Jamshid Derakhshan, Melvin Fitting, Dov Gabbay, Massoud Pourmahdian, and Adrian Rezus. ISBN: 1848903405 EAN: 9781848903401)

Gaßner: Computation over Algebraic Structures and a Classification of Undecidable Problems,  Mathematical Structures in Computer Science (2016), 1-28. DOI: 10.1017/S0960129516000116

Gaßner: Strong Turing Degrees for Additive BSS RAM's, Logical Methods in Computer Science, vol. 9(4:25)2013, 1-18. Online. DOI: 10.2168/LMCS-9(4:25)2013

Gaßner: The Separation of Relativized Versions of P and DNP for the Ring of the Reals, Journal of Universal Computer Science, vol. 16, no. 18 (2010), 2563-2568. DOI: 10.3217/jucs-016-18-2563

Gaßner: Oracles and Relativizations of the P =? NP Question for Several Structures, Journal of Universal Computer Science, vol. 15, no. 6 (2009), 1186-1205. DOI: 10.3217/jucs-015-06-1186

Gaßner: Relativizations of the P =? DNP Question for the BSS Model, Andrej Bauer, Peter Hertling, Ker-I Ko (eds.): 6th Int'l Conf. on Computability and Complexity in Analysis (2009), 141-148. DOI: 10.4230/OASIcs.CCA.2009.2266

Gaßner: On Relativizations of the P =? NP Question for Several Structures, Electronic Notes in Theoretical Computer Science  221 (2008), 71-83. DOI: 10.1016/j.entcs.2008.12.008

Gaßner: A Hierarchy below the Halting Problem for Additive Machines, Theory Computing Systems (2008), 464-470. DOI: 10.1007/s00224-007-9020-y

Gaßner: The P-DNP Problem for Infinite Abelian Groups, Journal of Complexity 17 (2001), 574-583. DOI: 10.1006/jcom.2001.0583

Gaßner: On NP-Completeness for Linear Machines, Journal of Complexity 13 (1997), 259-271. DOI: 10.1006/jcom.1997.0444

Gaßner: The Axiom of Choice in Second-Order Predicate Logic, Mathematical Logic Quarterly 40 (1994), 533-546. DOI: 10.1002/malq.19940400410

Gaßner, A. Pauly und F. Steinberg:  Computing Measures as a Primitive Operation,Daniel Graça and Martin Ziegler (eds.): Abstract Booklet „Computability & Complexity in Analysis“, CCA 2017, 26-27.

Gaßner:  BSS RAM's with \nu-Oracle and the Axiom of Choice. Colloquium Logicum 2016. Abstract.

Gaßner: Hierarchies of Decision Problems over Algebraic Structures Defined by Quantifiers. CCC 2015. Extended Abstract.

Gaßner und P. F. Valencia Vizcaíno: Operators for BSS RAM's (Contents: C. Gaßner, Speaker: P. F. Valencia Vizcaíno),  Akitoshi Kawamura  and Martin Ziegler (eds.): Abstract Booklet „Computability & Complexity in Analysis“ (CCA 2015), 24-26. Online.

Gaßner: A Strong Turing Reduction for Additive BSS RAMs, Arno Pauly, Robert Rettinger, Klaus Weihrauch (eds.): Abstract Booklet „Computability & Complexity in Analysis“, CCA 2012, 9-10. Online.

Gaßner: Computation over Algebraic Structures and Finitary Domains, Norbert Müller (ed.): CCC 2012, p. 26.

Gaßner: Computation over Algebraic Structures and the Turing Reduction, Norbert Müller (ed.): CCC 2012, 27-32.

Gaßner: A General BSS Model over Arbitrary Structures, Peter Hertling, Rod Downey, Vasco Brattka (eds.): Abstract Booklet „Computability & Complexity in Analysis (CCA 2011); Computability, Complexity & Randomness (CCR 2011)“, 12-14. Online.

Gaßner: Hierarchies below the Halting Problem for Additive Machines, Klaus Ambos-Spies, Benedikt Löwe, Wolfgang Merkle, (eds.): Mathematical Theory and Computational Practice (2009), p. 333.

Gaßner: Computation over Groups, Arnold Beckmann, Costas Dimitracopoulos, and Benedikt Löwe (eds.): Logic and Theory of Algorthms (2008), 147-156.

Gaßner: P = NP for Expansions Derived frome Some Oracles, S. Barry Cooper, Thomas F. Kent, Benedikt Löwe, and Andrea Sorbi (eds.): Computation and Logic in the Real World, CiE 2007, in the series Quaderni del Dipartimento di Scienze Matematiche e Informatiche "Roberto Magari" of the University of Siena. Technical report no. 487 June 2007, 161-169.

Gaßner: A Structure with P = NP, Computer Science Report Series, University of Wales Swansea, CSR 7 (2006), 85-94. 

Gaßner: Expansions of Structures with P = NP, Computer Science Report Series, University of Wales Swansea, CSR 7 (2006), 95-104.

U. Berger, V. Brattka, Gaßner, G. Gherardi, R. Hölzl, A. Pauly, R. Rettinger, P. Schlicht, M. Schröder, K. Seidel, F. Steinberg und X. Zheng: Computability and Reducibility.  Abstract Booklet, Preprint-Reihe Ag Berechenbarkeitstheorie über algebraischen Strukturen Greifswald, Preprint 2/2017.

A. Nies, V. Brattka, Gaßner, R. Hölzl, A. Pauly und P. Schlicht:  Computability and the BSS Model,  Abstract Booklet, Preprint-Reihe Ag Berechenbarkeitstheorie über algebraischen Strukturen Greifswald, Preprint 1/2016.

H. Diener, Gaßner, P. Schlicht, I. Schwende, D. Spreen: Computability and Logic. Preprint 4/2012.

H. Diener, Gaßner, P. Grieger, A. Pauly, C. Rösnick, P. Scheiblechner, P. Schlicht, I. Schwende, M. Ziegler: Different Models of Computation. Preprint 3/2011.

A. Beckmann, C. Gaßner, B. Löwe (eds.): Logical Approaches to Barriers in Computing and Complexity, International Workshop, Greifswald, Germany, February 2010. Preprint 6/2010.

For definitions, see also: 1, 2, 3

Gaßner: Degrees of Unsolvability for Additive BSS Machines. Preprint 3/2010.

Gaßner: Relativizations of the P =? DNP Question over the Complex Numbers. (cf. CCC 2009: Folien) 

Gaßner: On the Power of Relativized Versions of P, DNP, and NP for Groups. Preprint 8/2008.

Gaßner: From Structures with P ≠ NP to Structures with P = NP and Reverse.  Preprint 10/2006.

Gaßner: Padding of Strings, Small Strings, and the Decidability of an NP-complete Problem. Preprint 2/2006.

Gaßner: The Polynomial Hierarchy for Linear Real Machines (1996). Preprint 10/2005.

Gaßner: A Structure of Finite Signature with Identity Relation and with P = NP: A Formal Proof. Preprint 1/2005.

Gaßner: Eine Struktur endlicher Signatur mit Identitätsrelation und mit P = NP. Preprint 14/2004.

Gaßner: NP \subset DEC und P = NP für Expansionen von Erweiterungen von Strukturen endlicher Signatur mit Identitätsrelation. Preprint 13/2004.

Gaßner: A Structure of Finite Signature with P=NP: The Definitions. Preprint 2/2004. 04061 Abstract collection.

Gaßner: Über die Konstruktion von Strukturen endlicher Signatur mit P = NP. Preprint 1/2004.

Gaßner: Ein erweitertes Boxenmodell für Prolog. Preprint 2/2008 (researchgate)