and organizations (regimes, governments, parties, courts, etc.) that crystallize political interactions, formalize legal constraints and impose a degree of stability or inertia. Special importance is given to, first, the role of contexts, which confer meaning to trends and events, while shared contexts offer shared meanings; second, to changes over time in power relationships, and, subsequently, asymmetries, hierarchies, contention, or conflict; and, finally, to historical events that are able to shape trajectories, such as elections, accidents, inaugural speeches, treaties, revolutions, or ceasefires. Empirically, political sequences' unit of analysis can be individuals, organizations, movements, or institutional processes. Depending on the unit of analysis, the sample sizes may be limited few cases (e.g., regions in a country when considering the turnover of local political parties over time) or include a few hundreds (e.g., individuals' voting patterns). Three broad kinds of political sequences may be distinguished. The first and most common is careers, that is, formal, mostly hierarchical positions along which individuals progress in institutional environments, such as parliaments, cabinets, administrations, parties, unions or business organizations. We may name trajectories political sequences that develop in more informal and fluid contexts, such as activists evolving across various causes and social movements, or voters navigating a political and ideological landscape across successive polls. Finally, processes relate to non-individual entities, such as: public policies developing through successive policy stages across distinct arenas; sequences of symbolic or concrete interactions between national and international actors in diplomatic and military contexts; and development of organizations or institutions, such as pathways of countries towards democracy (Wilson 2014). Concepts A sequence s is an ordered list of elements (s1,s2,...,sl) taken from a finite alphabet A. For a set S of sequences, three sizes matter: the number n of sequences, the size a = |A| of the alphabet, and the length l of the sequences (that could be different for each sequence). In social sciences, n is generally something between a few hundreds and a few thousands, the alphabet size remains limited (most often less than 20), while sequence length rarely exceeds 100. We may distinguish between state sequences and event sequences, where states last while events occur at one time point and do not last but contribute possibly together with other events to state changes. For instance, the joint occurrence of the two events leaving home and starting a union provoke a state change from 'living at home with parents' to 'living