Perhaps you should try some spelling variations:
integer formulation » integral formulation, integral formulations, integer permutations
formulation problem » formulation problems, formation problem, population problem
https microarray » data microarray, cells microarray, chip microarray
microarray https » microarrays https, microarray chips, microscopy https
problem https » problem hips, problem has, problem hip

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• Performing a fuzzy search may retrieve terms with similar spellings: integer formulation problem https microarray https~.
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