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Kel Cheris is a gifted mathematician underemployed as an infantry officer. Shuos Jedao is the technological ghost of a genocidal general. Together, they fight crime, where "crime" is defined as heresy against the calendar. In Yoon Ha Lee's brilliant device, a calendar is a social contract from which physics - and hence, weaponry - flow.
Calendrical heresy disables these weapons and thus undermines the power of the state.
If you love bold, original world-building, reflections on colonialism, and complicated relationships between clever protagonists who have every reason to distrust one another, you'll eat up the Machineries of Empire
series as avidly as I did. If military SF and n-dimensional chess sound like a bit of a slog, see if you can stick with it anyway. The language and imagery are utterly gorgeous, and these very timely stories have a great deal to say about complicity, responsibility, and the mechanisms of societal control.