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Defining Cities: Using Networks to Measure and Predict City Size| old_uid | 13504 |
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| title | Defining Cities: Using Networks to Measure and Predict City Size |
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| start_date | 2014/02/25 |
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| schedule | 15h |
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| online | no |
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| location_info | salle 11 |
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| summary | In this talk, I will begin with the notion that as cities get bigger, they get more than proportionately richer. This is an old idea in economics and one of its progenitors. Alfred Marshall, at the end of the nineteenth century defined these notions as ‘economies of urban agglomeration’. More recently the group of researchers at Santa Fe, in particular Luis Bettencourt and Geoff West, have argued that within the confines of comparable entities – cities – that define urban systems, as they grow, their income increases at a rate which is more than proportionate to their size, that is, if their size increases by 100%, their income increases by some 112%. This is positive allometry or superlinear scaling as it is referred to and it has been demonstrated quite categorically for the US urban system comprising some 366 Metropolitan Statistical Areas. However in this talk, I will report the work of our group which has demonstrated equally conclusively that no such positive allometry exists for the UK urban system. Much of our analysis rests on the fact that it is extremely difficulty to define cities categorically with respect to their physical extent over which we need to measure their attributes – population, income etc. – and to this end we explore many thousands of realisations of UK cities, demonstrating that in general for most reasonable city sizes, there is no superlinearity – that is defining economies of agglomeration is problematic, while London is a massive outlier. This suggests that the world of the UK cities at least is much more complex than the US, and that one explanation is that the UK is one large, relatively integrated urban system – city even – while the US is still composed of distinct cities that have not yet become integrated in quite the same way that has happened in the UK. We develop these ideas using various definitions of cities, particularly as networks of streets that we explore using percolation theory.
Ce séminaire fera suite au 4ème atelier organisé dans le cadre du projet de l'ERC ReaDi - Henri Berestycki (9h45-12h, même lieu ; accueil en salle 9 à 9h15) |
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| responsibles | Berestycki, Nadal, Rosenstiehl |
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