For a given function 
over a partition of a given interval, the lower sum is the sum of box areas 
using the infimum 
of the function 
in each subinterval ![[x_(k-1),x_k]](/images/equations/LowerSum/Inline5.svg)
.
Lower Sum
See also
Lower Integral, Riemann Integral, Upper SumExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Lower Sum." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/LowerSum.html