摘要
The methods of distribution of inter-modulation-free frequencies for communication systems are of significance in engineering. By using these methods, we can repress the disturbance caused by nonlinearity and may use frequency resource sufficiently. On the basis of Refs. [1] and [2], we shall give the following mathematical description to the problem of distribution of inter-modulation-free frequencies. Suppose that ρ denotes the group of sequences S1,S2,…, Sl, where Si=(a1（i）, a2（i）,…, al（i）},
