Protests may erupt into riots.Logical formLearned from12 sentences. A world-city can be a scene of riots.Logical formLearned from12 sentences. Riots may break_out in a month.Logical formLearned from12 sentences. (Street battles) can be between (riot police).Logical formLearned from12 sentences. A night can be constituted-of-or-filled-with (youth riots).Logical formLearned from12 sentences. Units can be constituted-of-or-filled-with (riot police).Logical formLearned from12 sentences. A campaign may be marked by a riot.Logical formLearned from12 sentences. Memories of riots may linger.Logical formLearned from12 sentences. (Riot police) may carry batons.Logical formLearned from12 sentences. (Riot police) may break_up demonstrations.Logical formLearned from12 sentences. (Riot police) may use (water cannon).Logical formLearned from12 sentences. Protests may degenerate into riots.Logical formLearned from12 sentences. Racial riots can be in 1960s.Logical formLearned from12 sentences. Persons may be killed in riots.Logical formLearned from12 sentences. A riot can be by youths.Logical formLearned from12 sentences.