obstruction

n 1: anything that makes progress difficult [syn: {impediment}, {impedimenta}]

2: something immaterial that stands in the way and must be

circumvented or surmounted: "lack of immagination is an

obstacle to one's advancement"; "the poverty of a district

is an obstacle to good education"; "the filibuster was a

major obstruction to the success of their plan" [syn: {obstacle}]

3: the act of obstructing; "obstruction of justice"

4: getting in someone's way

abstraction

1. Generalisation; ignoring or hiding details to capture some

kind of commonality between different instances. Examples are

{abstract data types} (the representation details are hidden),

{abstract syntax} (the details of the {concrete syntax} are

ignored), {abstract interpretation} (details are ignored to

analyse specific properties).

2. Parameterisation, making something a function

of something else. Examples are {lambda abstractions} (making

a term into a function of some variable), {higher-order

function}s (parameters are functions), {bracket abstraction}

(making a term into a function of a variable).

Opposite of {concretisation}.

(1998-06-04)