Zoning for diversity As production becomes increasingly clean and knowledge-based, as our urban economies tip dramatically to service industries, as racism and ethnic animosities ebb, and as the model of mixed use becomes more and more persuasive and visible, cities are in a position to dramatically rethink zoning as a medium for leveraging and usefully complicating difference, rather than simply isolating it. Michael Sorkin, 20 Minutes in Manhattan zoningrace
The greatest flaw in city zoning Raskin, in his essay on variety, suggested that the greatest flaw in city zoning is that it permits monotony. I think this is correct. Perhaps the next greatest flaw is that it ignores scale of use, where this is an important consideration, or confuses it with kind of use. Jane Jacobs, The Death and Life of Great American Cities zoningmonotonyscale
The air doesn't know about zoning boundaries Work uses suggest another bugaboo: reeking smokestacks and flying ash. Of course reeking smokestacks and flying ash are harmful, but it does not follow that intensive city manufacturing (most of which produces no such nasty by-products) or other work uses must be segregated from dwellings. Indeed, the notion that reek or fumes are to be combated by zoning and land-sorting classifications at all is ridiculous. The air doesn’t know about zoning boundaries. Regulations specifically aimed at the smoke or the reek itself are to the point. Jane Jacobs, The Death and Life of Great American Cities zoningregulationsseparation
The problem with trees Many systems are organized hierarchically. The CERNDOC documentation system is an example, as is the Unix file system, and the VMS/HELP system. A tree has the practical advantage of giving every node a unique name. However, it does not allow the system to model the real world. For example, in a hierarchical HELP system such as VMS/HELP, one often gets to a lead on a tree such as: HELP COMPILER SOURCE_FORMAT PRAGMAS DEFAULTS only to find a reference to another leaf: Please see HELP COMPILER COMMAND OPTIONS DEFAULTS PRAGMAS and it is necessary to leave the system and re-enter it. What was needed was a link from one node to another, because in this case the information was not naturally organized into a tree. Tim Berners-Lee, Seeing With Fresh Eyes A City Is Not a Tree hierarchywww