(Riot police) may break_up a protest.Logical formLearned from21 sentences. A riot may undergo handling.Logical formLearned from21 sentences. (Riot police) can be on horseback.Logical formLearned from21 sentences. Riots may oust a president.Logical formLearned from21 sentences. Riots can be by (student groups).Logical formLearned from21 sentences. (Riot police) may be armed with rifles.Logical formLearned from21 sentences. (Riot police) may open fire.Logical formLearned from21 sentences. Some riots may expose a failure.Logical formLearned from21 sentences. Riots may be triggered.Logical formLearned from21 sentences. Thousands of (riot police) may be surrounded.Logical formLearned from21 sentences. Riots may spread.Logical formLearned from21 sentences. Riots may shake a world-city.Logical formLearned from21 sentences. A history can be constituted-of-or-filled-with riots.Logical formLearned from21 sentences. A (death toll) can be from riots.Logical formLearned from21 sentences. Response can be to a riot.Logical formLearned from20 sentences.