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She announced this surreptitiously in another forum:
http://www.democraticunderground.com/10021757160

Mathematics of Sex

My earlier thread on 'Oral Sex Etymology' appealed to one of the "Two Cultures" described by C. P. Snow. For proper balance, I thought it advisable to offer another thread which would appeal to the other "Culture", (i.e., nerdy, scientific types).

I shall grossly oversimplify the rich variety of human sexuality as follows: every person has one of two genders (M or F) and one of three orientations (S, G, or B). There are thus six types of people. Each entry in the following table is a '1' if the type of person indicated to the left can perform a particular act (designated by the letter 'C') on the type of person indicated above.
[font face="courier"]
    |   M   |   F   |
  C | S G B | S G B |
____|_______|_______|
  S | 0 0 0 | 1 0 1 |
M G | 0 0 0 | 0 0 0 |
  B | 0 0 0 | 1 0 1 |
____|_______|_______|
  S | 0 0 0 | 0 0 0 |
F G | 0 0 0 | 0 1 1 |
  B | 0 0 0 | 0 1 1 |
____|_______|_______|
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All the entries in the first three columns are zeros, because the act in question can only be performed on a female. All the entries in the fourth row are zeros, because a straight female would refuse to perform any sexual act on another female. Can you explain the other entries in the table?

Here are tables for two other acts that people sometimes perform on other people.
[font face="courier"]
    |   M   |   F   |
  F | S G B | S G B |
____|_______|_______|
  S | 0 0 0 | 0 0 0 |
M G | 0 1 1 | 0 0 0 |
  B | 0 1 1 | 0 0 0 |
____|_______|_______|
  S | 1 0 1 | 0 0 0 |
F G | 0 0 0 | 0 0 0 |
  B | 1 0 1 | 0 0 0 |
____|_______|_______|
[/font]
[font face="courier"]
    |   M   |   F   |
  T | S G B | S G B |
____|_______|_______|
  S | 0 0 0 | 0 0 0 |
M G | 0 0 0 | 0 0 0 |
  B | 0 0 0 | 0 0 0 |
____|_______|_______|
  S | 0 0 0 | 0 0 0 |
F G | 0 0 0 | 0 1 1 |
  B | 0 0 0 | 0 1 1 |
____|_______|_______|

Easy questions: what do the letters 'C' and 'F' stand for?
Harder question: what does the letter 'T' stand for?


On edit: Following is an advanced topic which assumes you know how to multiply matrices.
The 6 by 6 matrices C and F are related by a similarity transformation:

C = A F A  and  F = A C A,

where A is another 6 by 6 matrix:
     _           _
    |             |
    | 0 0 0 1 0 0 |
    | 0 0 0 0 1 0 |
A = | 0 0 0 0 0 1 | .
    | 1 0 0 0 0 0 |
    | 0 1 0 0 0 0 |
    | 0 0 1 0 0 0 |
    |_           _|

The matrix A represents a permutation which replaces males with females, and vice versa, while preserving the orientations S, G, B defined earlier. The matrix A is symmetric and is its own inverse, i.e.,

A A = I,

where I is the identity matrix:
     _           _
    |             |
    | 1 0 0 0 0 0 |
    | 0 1 0 0 0 0 |
I = | 0 0 1 0 0 0 | .
    | 0 0 0 1 0 0 |
    | 0 0 0 0 1 0 |
    | 0 0 0 0 0 1 |
    |_           _|

Oral Sex Etymology

For your amusement and edification, here are the etymologies of two clinical terms whose meanings are already familiar to you:

"fellatio"
ORIGIN late 19th cent.: modern Latin, from Latin fellare ‘to suck.’

"cunnilingus"
ORIGIN late 19th cent.: from Latin, from cunnus ‘vulva’ + lingere ‘lick.’

There is a vulgar word (which I won't repeat) that you might think was also derived from "cunnus", but the facts are otherwise:
ORIGIN Middle English : of Germanic origin; related to Norwegian and Swedish dialect "kunta", and Middle Low German, Middle Dutch, and Danish dialect "kunte".

Happy Darwin Day to our friends across the pond!

It's already 12 February over there. Charles Darwin was born on this date 203 years ago. He might have become a country parson with an amateurish interest in rocks and beetles. Instead he went on a voyage of discovery and became a celebrated naturalist, prolific writer, and co-discoverer of natural selection as the principal mechanism of organic evolution.

Astronomy in a parallel universe

Parallel universes, from branes to the many-worlds interpretation of quantum mechanics, are popular among theoretical physicists. This means that "what-if" scenarios in history are not entirely contrary to fact; they merely contradict the facts in our particular universe.

Consider the following example. In the late sixteenth century, Tycho Brahe observed a certain sixth-magnitude star. Continuing to observe this star over several years, Tycho made the startling discovery that it moved relative to the "fixed stars". Eureka, he had discovered a new planet! Since the discovery took place at his famous observatory Uraniborg, Tycho decided to call the planet "Uranus". Other astronomers were shocked at the news. Many of them couldn't see Uranus at all - they lacked the keen eyesight that Tycho was famous for. Some went so far as to deny the existence of Uranus, branding it a hoax. In time, other astronomers verified that Uranus was real, and the scholarly world came to accept its existence.

When the old king of Denmark died, Tycho had to confront a new, young monarch who was not interested in supporting astronomical research. Tycho was forced to look elsewhere for support, and he ended up at the court of Emperor Rudolph II in Prague. There he met a young astronomer named Kepler, who was also something of an exile. Kepler was not much of an observer, but he excelled at mathematical astronomy. Tycho gave Kepler the problem of computing the orbit of Mars. Out of this collaboration came Kepler's laws relating to elliptical planetary orbits.

In this universe, Kepler did not publish a book in 1600 containing the following figure:



As attractive as this explanation of the sizes of the planetary orbs was, it left no place for the planet Uranus. Kepler reluctantly decided that it was a false explanation, and he gave more attention to convincing Galileo and others that planetary orbits were indeed elliptical. As a result, the scientific revolution in this universe started earlier and went farther than in our universe.

Apple Inc. pays its CEO more, and those at the bottom less, than any other US company.

On the one hand, according to an AP story dated January 10, 2012,

Tim Cook could well end up being the highest-paid chief executive in the U.S. in 2011 after Apple Inc. granted him 1 million restricted stock units in August for taking the reins shortly before co-founder Steve Jobs died.

An Associated Press review of a securities filing shows that Cook's pay package was valued at $378 million.

come from places that do not make us better people for owning them, the factories in China where more than a dozen young workers have committed suicide, some by jumping; where workers must now sign a pledge stating that they will not try to kill themselves but if they do, their families will not seek damages; where three people died and fifteen were injured when dust exploded; where 137 people exposed to a toxic chemical suffered nerve damage; where Apple offers injured workers no recompense; where workers, some as young as thirteen, according to an article in The New York Times, typically put in seventy-two-hour weeks, sometimes more, with minimal compensation, few breaks, and little food, to satisfy the overwhelming demand generated by the theatrics, the marketing, the packaging, the consummate engineering, and the herd instinct; and where, it goes without saying, the people who make all this cannot afford to buy it?

While it may be convenient to suppose that Apple is no different than any other company doing business in China—which is as fine a textbook example of a logical fallacy as there is—in reality, it is worse. According to a study reported by Bloomberg News last January, Apple ranked at the very bottom of twenty-nine global tech firms “in terms of responsiveness and transparency to health and environmental concerns in China.”