Perhaps you should try some spelling variations:
"modified df optimization algorithm" » "modified df optimization algorithms", "modified df optimisation algorithm", "modified df estimation algorithm", "modified _ optimization algorithm", "modified qoe optimization algorithm", "modified _ optimisation algorithm", "modified adam optimization algorithm", "modified bi1 optimization algorithm"
"modified notion approximation algorithms" » "modified network approximation algorithms", "modified time approximation algorithms", "modified one approximation algorithms"

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