Type I superstring theory
= Type I superstring theory
{wiki=Type_I_string_theory}
An unoriented theory containing open and closed superstrings. Consistent gauge and gravitational anomaly cancellation yields the familiar $\mathfrak{so}(32)$ gauge algebra. Open-string <Chan-Paton factors> supply the gauge degrees of freedom, while closed strings contain gravity. It is related by strong/weak duality to the corresponding heterotic theory.