Proof Ground 2020

Interactive Proving Contests

This workshop brings together researchers of the ITP community to compete in a “proving contest”.

While programming contests (e.g. ACM ICPC, International Olympiad in Informatics) challenge large numbers of participants to solve algorithmic problems within a short time, we envision proving contests to entice proof engineers to formally prove small but interesting problems from mathematics or computer science.

A contest system is currently used for teaching and hosting proving contests in Coq, Isabelle, and Lean. We welcome the development of backends for any other Proof Assistants.

Proof Ground 2020 is part of the Paris Nord Summer of LoVe 2020, a joint event on LOgic and VErification at Université Paris 13, made of Petri Nets 2020, IJCAR 2020, FSCD 2020, and over 20 satellite events.

The workshop will be organized around an onsite contest, supplemented with informal presentations and discussions. As the main conferences of Paris Nord Summer of LoVe will happen as virtual conferences due to the Covid-19 outbreak, Proof Ground will also take a purely virtual format.

The first edition of the workshop has been held at ITP 2019.

Important Dates

Submission deadline: June 1, 2020

Workshop and Competition: June 29, 2020


The results of the competition are summarized here.


  1. Manuel Eberl
  2. Martin Raszyk
  3. Peter Lammich

A Github repository with solutions can be found here. Feel free to send us a pull request with your own (polished) solutions!


A summary of the results and a discussion of the problems.

Introduction slides.


Time What?
09:30-10:00 Intro and Q&A
10:00-10:20 Meet Your Competitors
10:20-10:30 Competition Preparation
10:30-12:30 Competition I
12:30-14:00 Lunch/Open Discussion
14:00-15:30 Competition II
15:30-16:00 Coffee Break/Open Discussion
16:00-17:00 Results & Plenary Discussion

All times refer to the CEST time zone.

Workshop day information

The contest phases will be organized through the competition system. Please register an account in advance.

Plenaries are happening on Zoom. You should already have received the link if you have registered for the workshop.

For coffee & lunch breaks, we will additionally use Discord. You can find the link to our Discord server on Zoom. Using Discord is not required but recommended.

Our tasks have been prepared for the following systems:


Maximilian P. L. Haslbeck

Simon Wimmer

Tobias Nipkow

Problem committee

Max Haslbeck

Simon Wimmer

Fabian Kunze

Simon Hudon

Kevin Kappelmann

Who Should Attend?

Due to its online nature, collaboration during the contest is discouraged. Participants should compete as individuals. We will at least provide automatic grading for Coq, Isabelle, and Lean, but participants that use other proof assistants can compete as well.

For the discussions, participation is open for anybody interested. We invite users and developer of all Proof Assistants to join in a discussion on how proving contests

Call for Problems

In order to conduct a stimulating contest we solicit interesting tasks.

A contest typically lasts for two hours and consists of around five problems with varying difficulty.

A problem:

Submissions from (potential) competition participants are allowed.

Examples can be found at the current “Proving for Fun” contest system, e.g. here.

Submissions can be made via email to wimmers [at] in [dot] tum [dot] de by the date indicated above.


Maximilian P. L. Haslbeck

Tobias Nipkow

Simon Wimmer