Стратегическое поведение в голосовании на выбывание: что мы можем узнать из выборов стран — хозяек чемпионатов мира FIFA 2018 и 2022 гг.?
Procedures aggregating individual preferences into a collective choice differ in their vulnerability to manipulations. To measure it, one may consider the share of preference profiles where manipulation is possible in the total number of profiles, which is called Nitzan-Kelly's index of manipulability. The problem of manipulability can be considered in different probability models. There are three models based on anonymity and neutrality: impartial culture model (IC), impartial anonymous culture model (IAC), and impartial anonymous and neutral culture model (IANC). In contrast to the first two models, the IANC model, which is based on anonymity and neutrality axioms, has not been widely studied. In addition, there were no attempts to derive the difference of probabilities (such as Nitzan-Kelly's index) in IC and IANC analytically. We solve this problem and show in which cases the upper bound of this difference is high enough, and in which cases it is almost zero. These results enable us to simplify the computation of indices.
When a society needs to take a collective decision one could apply some aggregation method, particularly, voting. One of the main problems with voting is manipulation. We say a voting rule is vulnerable to manipulation if there exists at least one voter who can achieve a better voting result by misrepresenting his or her preferences. The popular approach to comparing manipulability of voting rules is defining complexity class of the corresponding manipulation problem. This paper provides a survey into manipulation complexity literature considering variety of problems with different assumptions and restrictions.
The article analyses the effects of new transport infrastructure on transport systems of the 2018 FIFA World Cup host cities. The choice of cities is based on the scale of planned transport infrastructure – Saransk, Kaliningrad and Ekaterinburg experienced substantial interventions. Analysis is conducted using open spatial data on population and street networks. All interventions in transport infrastructure were evaluated in terms of their effectiveness and usefulness for the cities after the 2018 FIFA World Cup – scale of improvements in street network connectivity and accessibility of key places in the cities. We identified that investments into new transport infrastructure of Saransk seems to be the most effective in terms of future use. We demonstrated the feasibility of conducting such analysis using only open data, but also identified some issues and pitfalls.