Verma 1968: M(lambda) free U(n-)-module on highest-weight v_lambda; reducible iff lambda + rho is integral-dominant; Bernstein-Gelfand-Gelfand resolution.
Verma 1968: M(lambda) free U(n-)-module on highest-weight v_lambda; reducible iff lambda + rho is integral-dominant; Bernstein-Gelfand-Gelfand resolution.