Unwar

It was a movie about American bombers in the Second World War and the men who flew them. Seen backwards by Billy, the story went like this:

American planes, full of holes and wounded men and corpses took off backwards from an airfield in England. Over France, a few German fighter planes flew at them backwards, sucked bullets and shell fragments from some of the planes and crewmen. They did the same for wrecked American bombers on the ground, and those planes flew up backwards to join the formation.

The formation flew backwards over a German city that was in flames. The bombers opened their bomb bay doors, exerted a miraculous magnetism which shrunk the fires, gathered them into cylindrical steel containers, and lifted the containers into the bellies of the planes. The containers were stored neatly in racks. The Germans below had miraculous devices of their own, which were long steel tubes. They used them to suck more fragments from the crewmen and planes. But there were still a few wounded Americans, though, and some of the bombers were in bad repair. Over France, though, German fighters came up again, made everything and everybody as good as new.

When the bombers got back to their base, the steel cylinders were taken from the racks and shipped back to the United States of America, where factories were operating night and day, dismantling the cylinders, separating the dangerous contents into minerals. Touchingly, it was mainly women who did this work. The minerals were then shipped to specialists in remote areas. It was their business to put them into the ground, to hide them cleverly, so they would never hurt anybody ever again.

The American fliers turned in their uniforms, became high school kids. And Hitler turned into a baby, Billy Pilgrim supposed. That wasn’t in the movie. Billy was extrapolating. Everybody turned into a baby, and all humanity, without exception, conspired biologically to produce two perfect people named Adam and Eve, he supposed.

Kurt Vonnegut, Slaughterhouse-Five

The Gospel from Outer Space

It was The Gospel from Outer Space, by Kilgore Trout. It was about a visitor from outer space, shaped very much like a Tralfamadorian, by the way. The visitor from outer space made a serious study of Christianity, to learn, if he could, why Christians found it so easy to be cruel. He concluded that at least part of the trouble was slipshod storytelling in the New Testament. He supposed that the intent of the Gospels was to teach people, among other things, to be merciful, even to the lowest of the low.

But the Gospels actually taught this:

Before you kill somebody, make absolutely sure he isn’t well connected. So it goes.

The flaw in the Christ stories, said the visitor from outer space, was that Christ, who didn’t look like much, was actually the Son of the Most Powerful Being of the Universe. Readers understood that, so, when they came to the crucifixion, they naturally thought, and Rosewater read out loud again:

Oh, boy—they sure picked the wrong guy to lynch that time!

And then that thought had a brother: “There are right people to lynch.” Who? People not well connected. So it goes.

The visitor from outer space made a gift to Earth of a new Gospel. In it, Jesus really was a nobody, and a pain in the neck to a lot of people with better connections than he had. He still got to say all the lovely and puzzling things he said in the other Gospels.

So the people amused themselves one day by nailing him to a cross and planting the cross in the ground. There couldn’t possibly be any repercussions, the lynchers thought. The reader would have to think that, too, since the new Gospel hammered home again and again what a nobody Jesus was.

And then, just before the nobody died, the heavens opened up, and there was thunder and lightning. The voice of God came crashing down. He told the people that he was adopting the bum as his son, giving him the full powers and privileges of The Son of the Creator of the Universe throughout all eternity. God said this: From this moment on, He will punish horribly anybody who torments a bum who has no connections!

Kurt Vonnegut, Slaughterhouse-Five

Specifications for mathematics

Specification A function is a mathematical entity with the following properties:

  • f has domain and codomain, each of which must be a set.
  • For every element x of the domain, f has a value at x, which is an element of the codomain and is denoted f(x).
  • The domain, the codomain, and the value f(x) for each x in the domain are all determined completely by the function.
  • Conversely, the data consisting of the domain, the codomain, and the value f(x) for each element x of the domain completely determine the function f.

Functions in theory and practice

The concept of function can be explicity defined in terms of its domain, codomain and graph. Precisely, a function f : S → T could be defined as an ordered triple (S, Γ, T) with the property that Γ is a subset of the cartesian product S × T with the functional property (Γ is the graph of f). Then for x ∈ S, f(x) is the unique element y ∈ T for which (x,y) ∈ Γ. Such a definition clearly satisfies [the specification above].

The description of functions in [the specification above] is closer to the way a matematician thinks of a function than the definition [in the preceding paragraph]. For a matematician, a function has a domain and a codomain, and if x is in the domain, then there is a well defined value f(x) in the codomain. It is wrong to think that a function is actually an ordered triple as described in the preceding paragraph in the same sense that it is wrong for a programmer writing in a high level language to think of the numbers he deals with as being expressed in binary notation. The possible definition of functon in the preceding paragraph is an implementation of the specification for function, and just as with program specifications the expectation is that one normally works with the specification, not the implementation, in mind.

Michael Barr and Charles Wells, Category Theory for Computing Science