Twentieth International Conference on Computability and Complexity in Analysis

September 7-9, 2023, Dubrovnik, Croatia


(image of Dubrovnik taken from Wikipedia)

The conference CCA 2023 will be held as a hybrid meeting at the Inter-University Centre Dubrovnik.


The conference is concerned with the theory of computability and complexity over real-valued data.

Computability and complexity theory are two central areas of research in mathematical logic and theoretical computer science. Computability theory is the study of the limitations and abilities of computers in principle. Computational complexity theory provides a framework for understanding the cost of solving computational problems, as measured by the requirement for resources such as time and space. The classical approach in these areas is to consider algorithms as operating on finite strings of symbols from a finite alphabet. Such strings may represent various discrete objects such as integers or algebraic expressions, but cannot represent general real or complex numbers, unless they are rounded.

Most mathematical models in physics and engineering, however, are based on the real number concept. Thus, a computability theory and a complexity theory over the real numbers and over more general continuous data structures is needed. Despite remarkable progress in recent years many important fundamental problems have not yet been studied, and presumably numerous unexpected and surprising results are waiting to be detected.

Scientists working in the area of computation on real-valued data come from different fields, such as theoretical computer science, domain theory, logic, constructive mathematics, computer arithmetic, numerical mathematics and all branches of analysis. The conference provides a unique opportunity for people from such diverse areas to meet, present work in progress and exchange ideas and knowledge.

The topics of interest include foundational work on various models and approaches for describing computability and complexity over the real numbers. They also include complexity-theoretic investigations, both foundational and with respect to concrete problems, and new implementations of exact real arithmetic, as well as further developments of already existing software packages. We hope to gain new insights into computability-theoretic aspects of various computational questions from physics and from other fields involving computations over the real numbers.


  • Computable analysis
  • Complexity on real numbers
  • Constructive analysis
  • Domain theory and analysis
  • Effective descriptive set theory
  • Theory of representations
  • Computable numbers, subsets and functions
  • Randomness and computable measure theory
  • Models of computability on real numbers
  • Realizability theory and analysis
  • Reverse analysis
  • Weihrauch complexity
  • Real number algorithms
  • Implementation of exact real number arithmetic

Invited Speakers

Scientific Programme Committee

Organizing Committee

Schedule in Central European Summer Time (CEST)

Abstracts and Slides

Extended abstracts of the invited and contributed presentations and some slides of CCA 2023 can be found here:

Conference Picture

This group picture of CCA 2023 shows some participants:

CCA 2023 Group Picture


You can register for CCA 2023 (and pay the registration fee) on the following web page: The registration fee for regular participants (those who attend the conference in person) is 50 Euro and it can be also paid at the IUC office upon arrival. The registration fee for online participants is 25 Euro.


Authors are invited to submit 1-2 pages abstracts in PDF format, including references via the following web page: If full versions of papers are already available as technical report or arXiv version, then corresponding links should be added to the reference list. Final versions of abstracts might be distributed to participants in hardcopy and/or in electronic form.


Venue and Accommodation

The conference takes place at the Inter-University Centre Dubrovnik, Don Frana Bulica 4, HR-20000 Dubrovnik, Croatia.

The conference participants are kindly requested to book their own accommodation. For accommodation possibilities see


Dubrovnik is connected by daily flights to many European destinations. From Dubrovnik Airport you can take a shuttle bus and it will transfer you to the Old Town of Dubrovnik. The conference venue is only a few minutes walk away from the west gate of the Old Town (Pile gate).

CCA Steering Committee

Vasco Brattka, chair (Munich, Germany and Cape Town, South Africa), Peter Hertling (Munich, Germany), Akitoshi Kawamura (Kyoto, Japan), Klaus Weihrauch (Hagen, Germany), Ning Zhong (Cincinnati, USA), Martin Ziegler (Daejeon, Republic of Korea)

Further Information

For further information, please contact