Harrison C. White’s research while affiliated with Harvard University and other places

Looking at housing policy in terms of the careers of vacancies in the system offers a new perspective for deciding on program priorities. Available data indicate that the filtering process enables four families to move for every new unit built. The filtering process can be modeled using probabilities for the movement of housing vacancies. New vacancies are generated by the flow of families out of the metropolitan area as well as by the flow of new houses into the metropolitan stock.

The aim of this paper is to understand the interrelations among relations within concrete social groups. Social structure is sought, not ideal types, although the latter are relevant to interrelations among relations. From a detailed social network, patterns of global relations can be extracted, within which classes of equivalently positioned individuals are delineated. The global patterns are derived algebraically through a ‘functorial’ mapping of the original pattern. Such a mapping (essentially a generalized homomorphism) allows systematically for concatenation of effects through the network. The notion of functorial mapping is of central importance in the ‘theory of categories,’ a branch of modern algebra with numerous applications to algebra, topology, logic. The paper contains analyses of two social networks, exemplifying this approach.

In “small world” studies successive men each send on a postcard packet to an acquaintance who may know a designated target person on a first-name basis. In this analysis the likelihood of discarding the packet is separated from the chance the packet if sent reaches a man who knows the target. The former probability is assumed to be independent of the previous number of persons in the chain. The assumption is satisfied by the three extant sets of aggregate data. Then the latter probability is found to rise from zero to a modest plateau with the number of steps in the chain. Refinements and variants of the model are suggested. Funneling of chains through a few persons near the target is discussed.