A set of numbers , , ..., (mod ) form a complete set of residues, also called
a covering system, if they satisfy
See also Exact Covering System, Haupt-Exponent
References
Guy, R. K. ``Covering Systems of Congruences.'' §F13 in
Unsolved Problems in Number Theory, 2nd ed. New York: Springer-Verlag, pp. 251-253, 1994.