closure

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closure

1. Politics (in a deliberative body) a procedure by which debate may be halted and an immediate vote taken
2. Geology the vertical distance between the crest of an anticline and the lowest contour that surrounds it
3. Logic the closed sentence formed from a given open sentence by prefixing universal or existential quantifiers to bind all its free variables
4. Maths the smallest closed set containing a given set
5. Psychol the tendency, first noted by Gestalt psychologists, to see an incomplete figure like a circle with a gap in it as more complete than it is

closure

[′klō·zhər]
(civil engineering)
(geology)
The vertical distance between the highest and lowest point on an anticline which is enclosed by contour lines.
(mathematics)
The union of a set and its cluster points; the smallest closed set containing the set.
Property of a mathematical set such that a specified mathematical operation that is applied to elements of the set produces only elements of the same set

closure

(programming)
In a reduction system, a closure is a data structure that holds an expression and an environment of variable bindings in which that expression is to be evaluated. The variables may be local or global. Closures are used to represent unevaluated expressions when implementing functional programming languages with lazy evaluation. In a real implementation, both expression and environment are represented by pointers.

A suspension is a closure which includes a flag to say whether or not it has been evaluated. The term "thunk" has come to be synonymous with "closure" but originated outside functional programming.

closure

(theory)
In domain theory, given a partially ordered set, D and a subset, X of D, the upward closure of X in D is the union over all x in X of the sets of all d in D such that x <= d. Thus the upward closure of X in D contains the elements of X and any greater element of D. A set is "upward closed" if it is the same as its upward closure, i.e. any d greater than an element is also an element. The downward closure (or "left closure") is similar but with d <= x. A downward closed set is one for which any d less than an element is also an element.

("<=" is written in LaTeX as \subseteq and the upward closure of X in D is written \uparrow_\D X).
References in periodicals archive ?
3% annually through 2016 World demand for caps and closures is projected to rise 5.
Previous commissions on Base Realignment and Closure - BRAC - hit California hard, axing 29 major installations and cutting 100,000 defense-related jobs.
Closure-intensive Packaging Drives Sales of Caps and Closures in Western Europe
Table 3: Total Plastic Caps and Closures Market: Unit Forecasts by Closure Application (North America), 2009-2016
Defense Secretary Donald Rumsfeld has told military leaders he wants this round of base closures to do more than shutter unnecessary bases.
The Easy Open closure called RSH is produced at Closures Europe's Spanish site in Seville.
In November 2000, San Francisco voters rejected two ballot measures related to Saturday closures on John F.
Pentagon officials want more from the next round of base closures besides cutting surplus.
The 28mm closures are moulded in polypropylene in Sarson's traditional burgundy, and are produced from more flexible LDPE which offers capping efficiency on Nestl6's glass containers in comparison with the more rigid single piece polypropylene tamper evident closures previously used.
The Company expects that the closure of these stores should have a positive effect on the Company's profitability.
The organization is developing a plan to help defend the base against any attempts at closure and to better position the base to attract new programs and enhance its facilities.