First,we studied the invariance properties of the Kadomstev-Petviashvili equation with power law nonlinearity.Then,we determined the complete class of conservat
After being pumped from the 5s1/2 ground state to the 6p1/2 state,the population inversion between 6s1/2 and 5p1/2,3/2 can be established for a rubidium four-le