Perhaps you should try some spelling variations:
"modified notion approximation algorithms" » "modified network approximation algorithms", "modified time approximation algorithms", "modified one approximation algorithms"
"modified orcad solution algorithm" » "modified orcad evolution algorithm", "modified orcad convolution algorithms", "modified orcad evolutionary algorithm", "modified orca solution algorithm", "modified norway solution algorithm"

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• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified notion approximation algorithms") OR ("modified orcad solution algorithm"))~.
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