Many choice problems cannot be solved exactly and use several estimation algorithms that assign scores to the different available options. The estimation errors can have various correlations, from low (e.g. between two very different approaches) to high (e.g. when using a given algorithm with different hyperparameters). Most aggregation rules would suffer from this diversity of correlations. In this article, we introduce Embedded Voting (EV), an aggregation rule designed to take correlations into account, and we compare it to other aggregation rules in various experiments based on synthetic data. Our results show that when sufficient information about the correlations between errors is available, a maximum likelihood aggregation should be preferred. Otherwise, typically with limited training data, EV outperforms the other approaches.

We define a new class of low-communication voting rules, tailored for contexts with few voters and possibly many candidates. These rules are defined by a predefined sequence of voters: at each stage, the designated voter eliminates a candidate, and the last remaining candidate wins. We study both deterministic (non-anonymous) variants, and randomized (and anonymous) versions of these rules. We focus on a subfamily of these rules defined by ``non-interleaved'' sequences. We first focus on the axiomatic properties of our rules. Then we focus on the identification of the non-interleaved sequence that gives the best approximation of the Borda score under the impartial culture. Finally, we apply our rules to randomly generated data. Our conclusion is that, in contexts where there are more candidates than voters, elimination-based rules allow for a very low communication complexity (and especially, avoid asking voters to rank alternatives), and yet can be good approximations of common voting rules, while enjoying a number of good properties.

We present SVVAMP, a Python package dedicated to the study of voting systems with an emphasis on manipulation analysis.

We investigate the possibility of designing a voting rule that both meets the Condorcet criterion and has a low vulnerability to coalitional manipulation. For this purpose, we examine the Condorcification of a voting rule, where the original rule is altered to elect the Condorcet winner when one exists, and we study its impact on coalitional manipulability. A recent result states that for a large class of voting rules based on strict total orders, their Condorcification is at most as coalitionally manipulable as the original rule. We show that for most of them, the improvement is strict. We extend these results to a broader framework that includes weak orders and cardinal voting rules. These results support the main message of this paper: when searching for a “reasonable” voting rule with minimal coalitional manipulability, investigations can be restricted to Condorcet rules. In other words, in a class of “reasonnable” voting rules, it is possible to have both the Condorcet criterion and a minimal vulnerability to coalitional manipulation.

Internet is a large-scale and highly competitive economic ecosystem. In order to make fair decisions, while preventing the economic actors from manipulating the natural outcome of the decision process, game theory is a natural framework, and voting systems represent an interesting alternative that, to our knowledge, has not yet being considered. They allow competing entities to decide among different options. In this paper, we investigate their use for end-to-end path selection in multi-operator networks, analyzing their manipulability by tactical voting and their economic efficiency.We show that Instant Runoff Voting is much more efficient and resistant to tactical voting than the natural system which tries to get the economic optimum.