In behavioral economics, an internality is a type of behavior that imposes costs on a person in the long-run, that are not taken into account when first making decisions. Classical Economics discourages government from creating legislation that targets internalities, because it is assumed that the consumer takes these personal costs into account when paying for the good that causes the internality.
Herrnstein, R., Loewenstein, G., Prelec, D. & Vaughan, W. (1993). Utility maximization and melioration: Internalitites in individual choice. Journal of Behavioral Decision Making, 6, 149-185. http://onlinelibrary.wiley.com/doi/10.1002/bdm.3960060302/abstract
Structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as biological organisms, minerals and chemicals. Abstract structures include data structures in computer science and musical form. Types of structure include a hierarchy (a cascade of one-to-many relationships), a network featuring many-to-many links, or a lattice featuring connections between components that are neighbors in space.
The first book of Structures was begun in early 1951, as Boulez was completing his orchestral work Polyphonie X, and finished in 1952. It consists of three movements, or "chapters", labelled Ia, Ib, and Ic, composed in the order a, c, b. The first of the second book's two "chapters" was composed in 1956, but chapter 2 was not written until 1961. The second chapter includes three sets of variable elements, which are to be arranged to make a performing version (Häusler 1965, 5). A partial premiere of book 2 was performed by the composer and Yvonne Loriod at the Wigmore Hall, London, in March 1957. This was Boulez's first appearance in the UK as a performer (Griffiths 1973). The same performers gave the premiere of the complete second book, with two different versions of chapter 2, in a chamber-music concert of the Donaueschinger Musiktage on Saturday, 21 October 1961 (Südwestrundfunk n.d.).