Gauge and gravitational anomaly cancellation in type-I superstring theory

We present a comprehensive study of the gauge, mixed and gravitational anomalies in the type-I open superstring theory using the covariant RNS operator formalism. All anomalies are shown to cancel among the possible one-loop open string diagrams for the gauge group SO(32). Furthermore, we clear up some points that may not have been completely understood in the past and show how the anomaly contributions arise from the boundaries of moduli space. We also discuss how the open string calculations can be understood in the boundary and crosscap formalism. (orig.)