Shallow Ranking Formula

Higher score is better.
The score for a particular result is: $$\frac{1}{timesReturned}*\sum_{retrieved}{SE_{mul}*rankScore(retrieved.Rank)+SE_{const}}$$ $$+$$ $$10\ln (TRA * timesReturned + TRB)*TRC + TRD$$

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where $$rankScore(x) = \frac{100}{\sqrt{x*A+B}}*C+D$$ Note that by default: $$A=1, B=0, C=1, D=0$$ $$TRA=1, TRB=0, TRC=1, TRD=0$$ and $SE_{mul}$ and $SE_{const}$ depend on the $retrieved$ search engine, while the other variables are the same for all search engines.

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Taking the defaults into account, the formula simplifies to:

$$\frac{1}{timesReturned}*\sum_{retrieved}{(SE_{mul}*\frac{100}{\sqrt{retrieved.Rank}}+SE_{const})}+10\ln (timesReturned)$$