Superlinear scaling in cities, which appears in sociological quantities such
as economic productivity and creative output relative to urban population size,
has been observed but not been given a satisfactory theoretical explanation.
Here we provide a network model for the superlinear relationship between
population size and innovation found in cities, with a reasonable range for the
exponent.Comment: 5 pages, 5 figures, 1 table, submitted to Phys. Rev. E; references
corrected; figures corrected, references and brief discussion adde