Perhaps you should try some spelling variations:
approximation algorithm » approximation algorithms
optimisation algorithm » optimization algorithms, estimation algorithm, estimation algorithms
staffing optimisation » staffing optimization, static optimization
near approximation » one approximation, network approximation, _ approximation
modified staffing » modified caging
modified near » modified seird, modified adam

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• The words AND, OR and NOT may confuse the search; try adding quotes: "(( modified near approximation algorithm ) OR ( modified staffing optimisation algorithm ))~".
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