  Many computational problems in modern society account to probabilistic
reasoning, statistics, and combinatorics. A variety of these real-world
questions can be solved by representing the question in (Boolean) formulas and
associating the number of models of the formula directly with the answer to the
question. Since there has been an increasing interest in practical problem
solving for model counting over the last years, the Model Counting (MC)
Competition was conceived in fall 2019. The competition aims to foster
applications, identify new challenging benchmarks, and to promote new solvers
and improve established solvers for the model counting problem and versions
thereof. We hope that the results can be a good indicator of the current
feasibility of model counting and spark many new applications. In this paper,
we report on details of the Model Counting Competition 2020, about carrying out
the competition, and the results. The competition encompassed three versions of
the model counting problem, which we evaluated in separate tracks. The first
track featured the model counting problem (MC), which asks for the number of
models of a given Boolean formula. On the second track, we challenged
developers to submit programs that solve the weighted model counting problem
(WMC). The last track was dedicated to projected model counting (PMC). In
total, we received a surprising number of 9 solvers in 34 versions from 8
groups.
