Perhaps you should try some spelling variations:
approximation algorithm » approximation algorithms
objective solution » objective evolutionary, objective allocation
solution algorithm » evolution algorithm, convolution algorithms, evolutionary algorithm
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.

• The words AND, OR and NOT may confuse the search; try adding quotes: "(( modified objective solution algorithm ) OR ( modified df approximation algorithm ))~".
• Adding a wildcard symbol may retrieve word variants: (( modified objective solution algorithm ) OR ( modified df approximation algorithm ))*.