RAMBO on diet

We describe a phase space generator which is flat for massless particles, and approximately flat for massive particles of masses much smaller than the typical mometum scales involved in the process. The same goal is achieved by the RAMBO algorithm, contrary to which our approach does only require the minimal number of degrees of freedom and is invertible in the sense that it provides a unique mapping of random numbers to the physical phase space point and vice versa. The very motivation to seek such an algorithm is explained in detail.