# Let ε < 0.

## 09.9.09

### Mathematical limericks, vol. 1

Filed under: Harmonic analysis — Travis @

#### There once was a mathematician named x…

Mathematics: of sciences, queen
Has more rules than I’ve ever seen.
There are no exceptions,
Just number deceptions.
On calculators, I am quite keen.

A mathematician confided
That the Moebius band is one-sided
And you’ll get quite a laugh
If you cut one in half
‘Cause it stays in one piece when divided.

A mathematician named Klein
Thought the Moebius band was divine
Said he: “If you glue
The edges of two
You’ll get a weird bottle like mine.”

A go-go lap dancer, a pip,
Was able to peel in a zip.
And died of constriction
Attempting a Moebius strip.

The Moebius strip is a pain,
When you cut it again and again,
But if you should wedge
A large disk round the edge
Then you just get a projective plane.

If you have a cross-cap on your sphere,
And you give it a circle-shaped tear,
And untangle it out
And a Moebius strip will appear!

A mathematician named Crottle
Poured water into a Klein bottle.
That some will run out?”
He replied, “No, I don’t. Quite a lot’ll.”

There was young maiden named List
Whose mouth had a funny half-twist.
She’d turned both her lips
Into Moebius strips…
‘Til she’s kissed you, you haven’t been kissed!

There was a young fellow named Fisk,
A swordsman, exceedingly brisk.
So fast was his action,
The Lorentz contraction
Reduced his rapier to a disc.

A conjecture both deep and profound
Is whether the circle is round;
In a paper by Erdos,
written in Kurdish,
A counterexample is found.

A challenge for many long ages
Had baffled the savants and sages.
Yet at last came the light:
Seems old Fermat was right–
To the margin add 200 pages.

A calc student upset as could be
That his antiderivative didn’t agree
With the one in the book
E’en aft one more look.
Oh! Seems he forgot to write the “+ C”.

Computed the cube of infinity;
But it gave him the fidgets
To write down all those digits,
So he dropped math and took up divinity.

A mathematician called Bird,
Had students who thought him absurd.
There were cries of derision
When he said long division,
Meant one into one made a third.

A mathematician called Rumbold,
One day, quite by accident, stumbled
On the Meaning of Life,
Then went on, for his wife,
To find out why all her apple pies crumbled.

To a tightrope walker named Zekund
The a due to gravity beckoned.
His performance was great
Meters per second per second.

Consider the pitiful plight
Of a runner who wasn’t too bright.
For he sprinted so fast,
That he vanished at last
By red-shifting himself out of sight.

In the near-light speed space-ship I’m in,
I went rocketting off from my twin;
But since I’ve been away
I’ve aged hardly a day
And just look at the state that he’s in!

a vector-valued dominatrix
who divides a phase plane
into pleasure and pain
when she gets hold of more than one matrix. [CG]

Jack the mathematician
The problems he wrote,
He often would gloate,
Sen many a student a-wishin.’ [DG]

There once was a prof, Dr. K.,
Who taught calculus everyday.
From dawn until noon,
Integrating to the moon.
To him, derivatives were okay.

There was a prof named Kowalski
Who taught all this calculus to me.
On the final — no pass;
I must retake the class.
Why, we should all be so lucky. [ES]

Despite all the might fine teachin,’
I can’t help but find myself thinkin’
That Calculus I
Will be much more fun
The second time o’takin’. [MB]

Along cam Sir Isaac Newton
Doin’ mathematical computin’.
One day he contrived
To anti-derive
When findin’ signed areas is suitin’.

#### References

[CG] by Courtney Gibbons (of Brown Sharpie fame!).
[DG] by Dillon Glover.
[ES] by Eric Seifert.
[MB] by Matt Begeman.

## 09.8.09

### The kiss precise

Filed under: Harmonic analysis — Travis @

–Frederick Soddy

For pairs of lips to kiss maybe
Involves no trigonometry.
‘Tis not so when for circles kiss
Each one the other three.
To bring this off the four must be:
As three in one or one in three.
If one in three, beyond a doubt
Each gets three kisses from without.
If three in one, then is that one
Thrice kissed internally.

Four circles to the kissing come.
The smaller are the benter.
The bend is just the inverse of
The distance form the center.
Though their intrigue left Euclid dumb
There’s now no need for rule of thumb.
Since zero’s bend’s a dead straight line
And concave bends have minus sign,
The sum of the squares of all four bends
Is half the square of their sum.

To spy out spherical affairs
An oscular surveyor
And now besides the pair of pairs
A fifth sphere in the kissing shares.
Yet, signs and zero as before,
For each to kiss the other four
The square of the sum of all five bends
Is thrice the sum of their squares.

–A final verse by Thorold Gosset

And let us not confine our cares
To simple circles, planes and spheres,
But rise to hyper flats and bends
Where kissing multiple appears.
In n-ic space the kissing pairs
Are hyperspheres, and Truth declares-
As n+2 such osculate
Each with an (n+1)-fold mate.
The square of the sum of all the bends
Is n times the sum of their squares.

## 09.7.09

### If (math version)

Filed under: Harmonic analysis — Travis @

If you can solve a literal equation
And rationalize denominator surds,
Do grouping factors (with a transformation)
And state the factor theorem in words;
If you can plot the graph of any function
And do a long division (with gaps),
Or square binomials without compunction
Or work cube roots with logs without mishaps.
If you possess a sound and clear-cut notion
Of interest sums with P and i unknown;
If you can find the speed of trains in motion,
Given some lengths and “passing-times” alone;
If you can play with R (both big and little)
And feel at home with l (or h) and pi,
And learn by cancellation how to whittle
Your fractions down till they delight the eye.
If you can recognize the segment angles
Both at the center and circumference;
If you can spot equivalent triangles
And friend Pythagoras (his power’s immense);
If you can see that equiangularity
And congruence are two things and not one,
You may pick up a mark or two in charity
And, what is more, you may squeeze through, my son.

This appeared in the Times Educational Supplement, July 19, 1947.

## 09.6.09

### Haiku generator

Filed under: Harmonic analysis — Travis @

The haiku form is simple: a verse of 17 syllables, divided into three lines of five, seven, and five syllables respectively. The Western ear should note that the metrical unit is the syllable (Japanese is a syllabic language) and not, as in Western prosody, the foot composed of one or two syllables. The form of 17 syllables is not chance; it derives from the traditional view of Japanese linguistic philosophy that 17 syllables is the optimum length of human speech to be delivered clearly and coherently in one breathing.

All green in the leaves
I smell dark pools in the trees
Crash the moon has fled

All white in the buds
I flash snow peaks in the spring
Bang the sun has fogged

All starred in the cold
I seize thin trails in the mist
Look the oth has gone

The three examples above were produced by online man-machine interaction at the Cambridge Language Research Unit. The program provides a frame with “slots” in which the operator types words. His choice is constrained by the lists and arrow directions in the thesaurus and diagram (below). These show the semantic center of the poem, with five arrows going to it and one going from it, is situated at slot 5.

#### Semantic schema

```All [--1--] in the [--2--]
I [--3--] [--4--] [--5--] in the [--6--]
[--7--] the [--8--] has [--9--]
```

An asterisk * above indicates a double linkage. For the system to be computable, only one arrow may be chosen.

#### Conclusions

Here are two haiku written by human members of the NPL.

Pattern perception
Is easier to do than

Don’t design systems
Of automatic control.
Ride a bicycle.

Adapted from the catalog of the exhibition Cybernetic Serendipity: the Computers and teh Arts, Studio International, London 1968 p. 53; and NPL News 204, 10 (1967).

## 09.5.09

### Foundations of arithmetic

Filed under: Harmonic analysis — Travis @

–J. A. Lindon

One day when Mugg the Missing Link was prowling through the woods,
In search of wives and mammoth-meat and other useful goods,
Whom should he see, on pushing out from deep arboreal shade,
But Ogg, the Paleolithic Man, cross-legged in a glade.

This Ogg had made a neat array of pebbles on the ground,
In number they were twenty-one, the most that could be found,
And Ogg, with one red-hairy hand pressed to his bony brow,
Was staring at hese pebbles like a ruminating cow.

```           o o o o o o o
o o o o o o o
o o o o o o o
```

Thought Mugg – for he was Primitive – I should be very dull
To lose this opportunity of busting in his skull;
My club weighs half a hundredweigh, he doesn’t wear a hat
(And here he wondered) Yes, but what the devil is he at?

For Ogg was touching pebbles and then prodding at his digits,
Until the weirdness of it all afflicted Mugg with fidgets:
“Invented any goodish wheels just recently?” he hollered,
And doubled up in merriments, his face raw-beefy coloured.

Ogg looked at him in pity, then he drummed upon his chest:
“I’ve don a Think!” he bellowed “Monkey Mugg. I’ve done a think!
And I would write it down, but no one’s yet invented ink.”

Mugg moved a little closer, and his eyes and mouth were round,
And stared in trepidation at those pebbles on the ground.
Ogg pointed with a nailed red-hairy sausage at the rows
And said, “Three people’s hand-plus-two is hand-plus-feet-plus-nose.”

```oooo       oooo       oooo       oooo     oooo
o   +      o   +      o   =      o o       + ooooO Oooo + A
o          o          o
o          o          o
```

“And this is hand-plus-two of people’s three-for-each-by-name,
So three times hand-plus-two and hand-plus-to time three’s the same!”
Mugg scratched his matted hairy head, not knowing what to say.
Said Ogg, “It’s all made clear by this rectangular array.”

```                             o o o
o o o
o o o o o o o     o o o
o o o o o o o  =  o o o
o o o o o o o     o o o
o o o
o o o
```

“Three rows of hand-plus-two and hand-plus-two short rows of three
are just the same according to which way you look, you see?
In brief, a tripe heptad is the same as seven trebles,
And may quite possibly be true of other things than pebbles.”

Mugg viewed it from all angles, then he gave a raucous belch
And trod on a Batrachian that perished with a squelch.
He growled, “I do not understand these arithmetic quirks,
But maybe we should try to discover if it works.”

So home they went to get their wives and drag them by the hair,
But what with all their screeching and their running every way,
At first they would not form a neat rectangular array.

So Ogg he then positioned each by holding of her down
While Mugg with mighty club in hand, just dinted in her crown;
And when they had them all in place, like pebbles, they could see
That three times hand-plus-two in wives was hand-plus-two times three!

```      o<= o<= =>o =>o o<= o<= =>o

=>o o<= o<= =>o o<= o<= =>o

o<= =>o =>o o<= =>o o<= =>o
```

Then Ogg he roared in high delight, cartwheeling to and fro
(Carts had not been invented, but he did it just to show!),
And Mugg he grinned a shaggy grin and slapped a hairy thigh
And said, “It’s true, as sure as Pterodactyls learned to fly!”

And then they feasted on their wives in unuxorious zest,
Exept for one whose skull was rather thicker than the rest,
And she was sent to dig a pit and bury every bone,
While Mugg and Ogg went off to find a flat unsullied stone.

Then Ogg he sharpened up a flint and scratched upon the rock:
First Arithmetic Theorem – by Ogg the son of Mok.
He drew his little diagram, and proved, with QED,
That three times hand-plus-two of x is hand-plus-two times three.

But Mugg the Missing Link grew bored, and left him there alone,
Still scratching with his silly flint upon his silly stone;
And belching, plunged back in the woods on feet toe’s simple fives,
In search of wives and mammoth-meat, particularly wives!

## 09.4.09

### Hilbert space (a sonnet)

Filed under: Harmonic analysis — Travis @

–Lee Herron, Haverford College, 2003

We’ve studied oscillators big and small
With pendulum and breathing modes embraced
But there’s another way to grasp it all,
With normal modes as vectors in a space.
This inner product space holds many keys.
Where basis vectors sum to give us clues
‘Bout how to wield our normal modes with ease,
And thus, solutions to our Diff. EQs.
Used often in describing quantum states,
Indeed a daunting subject it subtends.
But with the vector math it correlates,
One sees its usefulness needs no defense.
Without it, where we’d be, I cannot place.
Its name, known far and wide, is Hilbert Space.

## 09.3.09

### Euclid drew a circle

Filed under: Harmonic analysis — Travis @

–Vachel Lindsay

Old Euclid drew a circle
On a sand-beach long ago.
He bounded and enclosed it
With angles thus and so.
His set of solemn greybeards
Nodded and argued much
Of arc and of circumference,
Diameter and such.
A silent child stood by them
From morning until noon
Because they drew such charming
Round pictures of the moon.

## 09.2.09

### Error message haiku

Filed under: CS silliness, Harmonic analysis — Travis @

In Japan, they have replaced the impersonal and unhelpful Microsoft error messages with Haiku poetry messages. Haiku poetry has strict construction rules. Each poem has only three lines, 17 syllables: five syllables in the first line, seven in the second, five in the third. Haiku is used to communicate a timeless message often achieving a wistful, yearning and powerful insight through extreme brevity — the essence of Zen:

```    A crash reduces
To a simple stone.

Chaos reigns within.
Reflect, repent, and reboot.
Order shall return.

First snow, then silence.
This thousand-dollar screen dies
So beautifully.

Having been erased,
The document you're seeking
Must now be retyped.

Out of memory.
We wish to hold the whole sky,
But we never will.

Program aborting:
Close all that you have worked on.

Serious error.
All shortcuts have disappeared.
Screen. Mind. Both are blank.

Stay the patient course.
Of little worth is your ire.
The network is down.

The Tao that is seen
Is not the true Tao -- until
You bring fresh toner.

The Website you seek
Cannot be located, but
Countless more exist.

Three things are certain:
Death, taxes and lost data.
Guess which has occurred.

Windows NT crashed.
I am the Blue Screen of Death.

With searching comes loss
And the presence of absence:

Yesterday it worked.
Today it is not working.
Windows is like that.

You step in the stream,
But the water has moved on.

It might be very useful.
But now it is gone.
```

This was sent to me by Laura “RuneMercury” H.

## 09.1.09

### Epigrams

Filed under: Harmonic analysis, Science humor — Travis @

Nature and Nature’s laws lay hid in night.
God said, “Let Newton be!” and all was light.
Alexander Pope

It did not last: the Devil howling “Ho!
Let Einstein be!” restored the status quo.
Sir John Collins Squire