A function 
is said to have a upper bound 
if 
for all 
in its domain. The least
upper bound is called the supremum. A set is said
to be bounded from above if it has an upper
bound.
Upper Bound
See also
Bounded from Above, Inequality, Infimum, Least Upper Bound, Lower Bound, SupremumPortions of this entry contributed by Todd Rowland
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Cite this as:
Rowland, Todd and Weisstein, Eric W. "Upper Bound." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/UpperBound.html