If a field has the property that, if the sets 
, ..., 
, ... belong to it, then so do the sets 
and 
, then the field is called a Borel field (Papoulis
1984, p. 29).
Borel Field
See also
FieldExplore with Wolfram|Alpha
References
Papoulis, A. Probability, Random Variables, and Stochastic Processes, 2nd ed. New York: McGraw-Hill, 1984.Referenced on Wolfram|Alpha
Borel FieldCite this as:
Weisstein, Eric W. "Borel Field." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/BorelField.html