Cantor
from
The Free On-line Dictionary of Computing (8 July 2008)
Cantor
1. <person, mathematics> A mathematician.
Cantor devised the diagonal proof of the uncountability of the
{real numbers}:
Given a function, f, from the {natural numbers} to the {real
numbers}, consider the real number r whose binary expansion is
given as follows: for each natural number i, r's i-th digit is
the complement of the i-th digit of f(i).
Thus, since r and f(i) differ in their i-th digits, r differs
from any value taken by f. Therefore, f is not {surjective}
(there are values of its result type which it cannot return).
Consequently, no function from the natural numbers to the
reals is surjective. A further theorem dependent on the
{axiom of choice} turns this result into the statement that
the reals are uncountable.
This is just a special case of a diagonal proof that a
function from a set to its {power set} cannot be surjective:
Let f be a function from a set S to its power set, P(S) and
let U = { x in S: x not in f(x) }. Now, observe that any x in
U is not in f(x), so U != f(x); and any x not in U is in f(x),
so U != f(x): whence U is not in { f(x) : x in S }. But U is
in P(S). Therefore, no function from a set to its power-set
can be surjective.
2. <language> An {object-oriented language} with fine-grained
{concurrency}.
[Athas, Caltech 1987. "Multicomputers: Message Passing
Concurrent Computers", W. Athas et al, Computer 21(8):9-24
(Aug 1988)].
(1997-03-14)
from
Moby Thesaurus II by Grady Ward, 1.0
64 Moby Thesaurus words for "cantor":
Heldentenor, Levite, Meistersinger, alto, aria singer, baal kore,
baritenor, baritone, bass, basso, basso buffo, basso cantante,
basso profundo, blues singer, canary, cantatrice, caroler, chanter,
chantress, chief rabbi, choir chaplain, choirmaster,
choral director, chorister, coloratura soprano, comic bass,
contralto, countertenor, crooner, deep bass, diva,
dramatic soprano, heroic tenor, high priest, hymner, improvisator,
kohen, lead singer, lieder singer, melodist, mezzo-soprano,
minister of music, opera singer, precentor, priest, prima donna,
psalm singer, rabbi, rabbin, rock-and-roll singer, scribe, singer,
singstress, songbird, songster, songstress, soprano, tenor,
torch singer, vocalist, vocalizer, voice, warbler, yodeler
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