Perhaps you should try some spelling variations:
optimization algorithms » optimisation algorithm, estimation algorithms, estimation algorithm
approximation algorithm » approximation algorithms
quantile optimization » quantile estimation, quadratic optimization, static optimization
modified quantile » modified adaptive
df approximation » _ approximation, one approximation, time approximation
modified df » modified _, modified adam, modified bi1

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (( modified df approximation algorithm ) OR ( modified quantile optimization algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (( modified df approximation algorithm ) or ( modified quantile optimization algorithms ))*.