Cantor

the religious official of a synagogue who conducts the liturgical portion of a service and sings or chants the prayers and parts of prayers designed to be performed as solos.
an official whose duty is to lead the singing in a cathedral or in a collegiate or parish church; a precentor.
Eddie (Edward Israel Iskovitz) 1892–1964, U.S. singer and entertainer.
Georg
[gey-awrk] /geɪˈɔrk/ (Show IPA), 1845–1918, German mathematician, born in Russia.
Contemporary Examples

The Dems Aren’t Toast Kirsten Powers September 22, 2010
What Science Reveals About Pedophilia Casey Schwartz December 6, 2011
Paul Ryan Breaks Rank John Batchelor September 25, 2010
John Boehner’s GOP Headaches Benjamin Sarlin, Samuel P. Jacobs January 5, 2011
Speed Read: Juiciest Bits From Bob Woodward’s Book ‘Price of Politics’ Miranda Green September 5, 2012

Historical Examples

Cousin Henry Anthony Trollope
Cousin Henry Anthony Trollope
Cousin Henry Anthony Trollope
Cousin Henry Anthony Trollope
Simon Eichelkatz; The Patriarch Ulrich Frank

noun
(Judaism) Also called chazan. a man employed to lead synagogue services, esp to traditional modes and melodies
(Christianity) the leader of the singing in a church choir
n.

1. 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. 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)