'Leaky abstractions': I think its the wrong question if an abstraction leaks or not; any abstraction is leaky by definition, an abstraction is created by omitting details that are not relevant to the analysis, with the wish to extract the essence; The right question is if the abstraction is relevant or not.
Wikipedia says:
http://en.wikipedia.org/wiki/Abstraction
"Abstraction in mathematics is the process of extracting the underlying essence of a mathematical concept, removing any dependence on real world objects with which it might originally have been connected, and generalizing it so that it has wider applications or matching among other abstract descriptions of equivalent phenomena."
Wikipedia says:
http://en.wikipedia.org/wiki/Abstraction "Abstraction in mathematics is the process of extracting the underlying essence of a mathematical concept, removing any dependence on real world objects with which it might originally have been connected, and generalizing it so that it has wider applications or matching among other abstract descriptions of equivalent phenomena."