Erdős–Bacon number

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A person's Erdős–Bacon number is the sum of their Erdős number—which measures the "collaborative distance" in authoring academic papers between that person and Hungarian mathematician Paul Erdős—and their Bacon number—which represents the number of links, through roles in films, by which the person is separated from American actor Kevin Bacon. The lower the number, the closer a person is to Erdős and Bacon, which reflects a small world phenomenon in academia and entertainment. The lowest possible achievable Erdős–Bacon number is 2, but had Paul Erdős and Kevin Bacon both co-authored a paper and appeared in a film together, they each would have had a Erdős–Bacon of 1. To have a defined Erdős–Bacon number, it is necessary to have both appeared in a film and co-authored an academic paper, although this in and of itself is not sufficient as one's co-authors must have a known chain leading to Paul Erdős, and one's film must have actors eventually leading to Kevin Bacon.

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