Internal Sets in The Ultrapower Construction
Relative to the ultrapower construction of the hyperreal numbers as equivalence classes of sequences, an internal subset of *R is one defined by a sequence of real sets, where a hyperreal is said to belong to the set if and only if the set of indices n such that, is a member of the ultrafilter used in the construction of *R.
More generally, an internal entity is a member of the natural extension of a real entity. Thus, every element of *R is internal; a subset of *R is internal if and only if it is a member of the natural extension of the power set of R; etc.
Read more about this topic: Internal Set
Famous quotes containing the words internal, sets and/or construction:
“You will see Coleridge—he who sits obscure
In the exceeding lustre and the pure
Intense irradiation of a mind,
Which, with its own internal lightning blind,
Flags wearily through darkness and despair—
A cloud-encircled meteor of the air,
A hooded eagle among blinking owls.”
—Percy Bysshe Shelley (1792–1822)
“bars of that strange speech
In which each sound sets out to seek each other,
Murders its own father, marries its own mother,
And ends as one grand transcendental vowel.”
—Randall Jarrell (1914–1965)
“No real “vital” character in fiction is altogether a conscious construction of the author. On the contrary, it may be a sort of parasitic growth upon the author’s personality, developing by internal necessity as much as by external addition.”
—T.S. (Thomas Stearns)