Captured Comet Becomes Moon of Jupiter

An anonymous reader writes 'Jupiter's gravity captured a comet in the mid-20th century, holding it in orbit as a temporary moon for 12 years. The comet, named 147P/Kushida-Muramatsu, is the fifth body known to have been pulled by Jupiter from its orbit around the Sun. The discovery adds to our understanding of how Jupiter interferes with objects from the 'Hilda group,' which are asteroids and comets with orbits related to Jupiter's orbit.'

Comments

Re:The comet's shape

[clone53421]

I'd say it's doubly redundant. Primes are, by definition, both nonzero and positive.

Nonzero and positive are only slightly redundant themselves, since mathematics will only occasionally deal with positive and negative zero. Computers may also consider zero to be a positive number, so "nonzero and positive" might not be redundant in computing.

Re:The comet's shape

[aldo.gs]

I'd say it's doubly redundant. Primes are, by definition, both nonzero and positive.

Since the OP is talking about "positive" (meaning that there are also "negative" numbers) he's talking about the integers. And since the integers are an integral domain the definition of primality becomes the definition for integral domain:

If p is a non-zero non-unit, we say that p is a prime element if, whenever p divides a product ab, then p divides a or p divides b

So it's actually not redundant.

 
Oh, god, what have I become...

Re:The comet's shape

[aldo.gs]

Sorry for the self-reply, but I meant that the "positive" condition is not redundant. The nonzero condition is redundant all right.

Re:The comet's shape

[clone53421]

Prime number:

In mathematics, a prime number (or a prime) is a natural number which has exactly two distinct natural number divisors: 1 and itself.

Natural number:

In mathematics, there are two conventions for the set of natural numbers: it is either the set of positive integers {1, 2, 3, ...} according to the traditional definition or the set of non-negative integers {0, 1, 2, ...} according to a definition first appearing in the nineteenth century.

Every prime number is a natural number, and every natural number is a positive/non-negative (depending on which definition you choose) integer. "Positive prime" is redundant.