sentences:  According to Donatella della Porta and Sidney Tarrow, the mechanism that produces violence in the declining phase of the collective action cycle is a result of the competition that arises among different sectors of the social movement.Together they formed a theory stating that as mass mobilization winds down, political violence rises in magnitude and intensity.In his study of the wave of mass protests that took place in Italy between 1965 and 1975, Sidney Tarrow stated that “[i]n the final stages of the cycle, there was an increase in the deliberate use of violence against others.