# UUCP Gernot jokes Math Jokes Jun

## Found at: 0x1bi.net:70/textfiles/file?humor/lions.cat

Article 343 of eunet.jokes:

From: heiser@ethz.UUCP (Gernot Heiser)

Newsgroups: rec.humor,sci.math,eunet.jokes

Subject: Re: Math Jokes

Message-ID: <464@ethz.UUCP>

Date: 4 Jun 88 12:08:44 GMT

References: <3440@pasteur.Berkeley.Edu> <2932@phoenix.Princeton.EDU> <1155@bentley.UUCP> <1156@bentley.UUCP> <546@osupyr.mast.ohio-state.edu> <583@picuxa.UUCP>

Reply-To: heiser@iis.UUCP (Gernot Heiser)

Organization: ETH Zuerich, Switzerland

Lines: 184

The following is from a book whose title I don't recall. The book is in German

but the article is actually a translation from the original by H. Petard which

appared in the American Monthly 54, 466 (1938). Unfortunately our library is

lacking some years of this journal around WW 2, so I had to re-translate the

German translations of books on Einstein which also usually re-translate

Einstein's words :-) ).

A Contribution to the Mathematical Theory of Big Game Hunting

=============================================================

We place a locked cage onto a given point in the desert. After that we

ntroduce the following logical system:

Axiom 1: The set of lions in the Sahara is not empty.

Axiom 2: If there exists a lion in the Sahara, then there exists a lion in

the cage.

Procedure: If P is a theorem, and if the following is holds:

"P implies Q", then Q is a theorem.

Theorem 1: There exists a lion in the cage.

We place a spherical cage in the desert, enter it and lock it from inside. We

then performe an inversion with respect to the cage. Then the lion is inside

the cage, and we are outside.

Without loss of generality we can view the desert as a plane surface. We

of the cage. Thereby the lion is mapped onto that same point.

Divide the desert by a line running from north to south. The lion is then

either in the eastern or in the western part. Lets assume it is in the eastern

n the northern or in the southern part. Lets assume it is in the northern

each step an increasingly narrow fence around the selected area. The diameter

of the chosen partitions converges to zero so that the lion is caged into a

fence of arbitrarily small diameter.

We observe that the desert is a separable space. It therefore contains an

enumerable dense set of points which constitutes a sequence with the lion as

ts limit. We silently approach the lion in this sequence, carrying the proper

equipment with us.

been proven [1] that such a curve can be traversed in arbitrarily short time.

Now we traverse the curve, carrying a spear, in a time less than what it takes

the lion to move a distance equal to its own length.

We observe that the lion possesses the topological gender of a torus. We embed

the desert in a four dimensional space. Then it is possible to apply a

We examine a lion-valued function f(z). Be \zeta the cage. Consider the integral

1 [ f(z)

------- I --------- dz

2 \pi i ] z - \zeta

C

s a lion in the cage [3].

We obtain a tame lion, L_0, from the class L(-\infinity,\infinity), whose

fourier transform vanishes nowhere. We put this lion somewhere in the desert.

L_0 then converges toward our cage. According to the general Wiener-Tauner

theorem [4] every other lion L will converge toward the same cage.

(Alternatively we can approximate L arbitrarily close by translating L_0

through the desert [5].)

We assert that wild lions can ipso facto not be observed in the Sahara desert.

Therefore, if there are any lions at all in the desert, they are tame. We leave

catching a tame lion as an execise to the reader.

At every instant there is a non-zero probability of the lion being in the cage.

Sit and wait.

t and a wild lion.

As a variant let us assume that we would like to catch (for argument's sake) a

male lion. We insert a tame female lion into the cage and apply the Heisenberg

exchange operator [7], exchanging spins.

All over the desert we distribute lion bait containing large amounts of the

companion star of Sirius. After enough of the bait has been eaten we send a

beam of light through the desert. This will curl around the lion so it gets all

confused and can be approached without danger.

We construct a semi-permeable membrane which lets everything but lions pass

through. This we drag across the desert.

We irradiate the desert with slow neutrons. The lion becomes radioactive and

the lion will be unable to resist.

We plant a large, lense shaped field with cat mint (nepeta cataria) such that

ts axis is parallel to the direction of the horizontal component of the

earth's magnetic field. We put the cage in one of the field's foci. Throughout

the desert we distribute large amounts of magnetized spinach (spinacia

oleracea) which has, as everybody knows, a high iron content. The spinach is

eaten by vegetarian desert inhabitants which in turn are eaten by the lions.

Afterwards the lions are oriented parallel to the earth's magnetic field and

the resulting lion beam is focussed on the cage by the cat mint lense.

[1] After Hilbert, cf. E. W. Hobson, "The Theory of Functions of a Real

Variable and the Theory of Fourier's Series" (1927), vol. 1, pp 456-457

[2] H. Seifert and W. Threlfall, "Lehrbuch der Topologie" (1934), pp 2-3

[3] According to the Picard theorem (W. F. Osgood, Lehrbuch der

Funktionentheorie, vol 1 (1928), p 178) it is possible to catch every lion

except for at most one.

[4] N. Wiener, "The Fourier Integral and Certain of itsl Applications" (1933),

pp 73-74

[5] N. Wiener, ibid, p 89

[6] cf e.g. H. A. Bethe and R. F. Bacher, "Reviews of Modern Physics", 8

(1936), pp 82-229, esp. pp 106-107

[7] ibid

--

Gernot HeiserPhone: +41 1/256 23 48

ETH Zuerich EARN/BITNET: GRIDFILE@CZHETH5A

CH-8092 Zuerich, Switzerland EUNET/UUCP: {uunet,...}!mcvax!ethz!iis!heiser

Article 426 of eunet.jokes:

From: steven@cwi.nl (Steven Pemberton)

Newsgroups: eunet.jokes

Subject: Re: Catching a Lion with computer science

Message-ID: <388@piring.cwi.nl>

Date: 6 Jul 88 11:24:18 GMT

References: <2024@sics.se>

Reply-To: steven@cwi.nl (mcvax!steven.uucp)

Distribution: eunet

Organization: CWI, Amsterdam

Lines: 66

Linear search:

Stand in the top left hand corner of the Sahara Desert. Take one step

east. Repeat until you have found the lion, or you reach the right

before you manage to get it in the cage, press the reset button, and

try again.

Dijkstra approach:

The way the problem reached me was: catch a wild lion in the Sahara

Desert. Another way of stating the problem is:

Axiom 1: Sahara elem deserts

Axiom 2: Lion elem Sahara

Axiom 3: NOT(Lion elem cage)

We observe the following invariant:

P1: C(L) v not(C(L))

Establishing C initially is trivially accomplished with the statement

;cage := {}

Note 0.

This is easily implemented by opening the door to the cage and

(End of note 0.)

The obvious program structure is then:

;cage:={}

;do NOT (C(L)) ->

;"approach lion under invariance of P1"

;if P(L) ->

;"insert lion in cage"

[] not P(L) ->

;skip

;fi

;od

Note 1.

Axiom 2 ensures that the loop terminates.

(End of note 1.)

Exercise 0.

Refine the step "Approach lion under invariance of P1".

(End of exercise 0.)

Note 2.

The program is robust in the sense that it will lead to abortion if

the value of L is "lioness".

(End of note 2.)

Remark 0.

This may be a new sense of the word "robust" for you.

(End of remark 0.)

Note 3.

From observation we can see that the above program leads to the

(End of note 3.)

(End of approach.)

Steven Pemberton, CWI, Amsterdam; steven@cwi.nl

Article 426 of eunet.jokes:

From: steven@cwi.nl (Steven Pemberton)

Newsgroups: eunet.jokes

Subject: Re: Catching a Lion with computer science

Message-ID: <388@piring.cwi.nl>

Date: 6 Jul 88 11:24:18 GMT

References: <2024@sics.se>

Reply-To: steven@cwi.nl (mcvax!steven.uucp)

Distribution: eunet

Organization: CWI, Amsterdam

Lines: 66

Linear search:

Stand in the top left hand corner of the Sahara Desert. Take one step

east. Repeat until you have found the lion, or you reach the right

before you manage to get it in the cage, press the reset button, and

try again.

Dijkstra approach:

The way the problem reached me was: catch a wild lion in the Sahara

Desert. Another way of stating the problem is:

Axiom 1: Sahara elem deserts

Axiom 2: Lion elem Sahara

Axiom 3: NOT(Lion elem cage)

We observe the following invariant:

P1: C(L) v not(C(L))

Establishing C initially is trivially accomplished with the statement

;cage := {}

Note 0.

This is easily implemented by opening the door to the cage and

(End of note 0.)

The obvious program structure is then:

;cage:={}

;do NOT (C(L)) ->

;"approach lion under invariance of P1"

;if P(L) ->

;"insert lion in cage"

[] not P(L) ->

;skip

;fi

;od

Note 1.

Axiom 2 ensures that the loop terminates.

(End of note 1.)

Exercise 0.

Refine the step "Approach lion under invariance of P1".

(End of exercise 0.)

Note 2.

The program is robust in the sense that it will lead to abortion if

the value of L is "lioness".

(End of note 2.)

Remark 0.

This may be a new sense of the word "robust" for you.

(End of remark 0.)

Note 3.

From observation we can see that the above program leads to the

(End of note 3.)

(End of approach.)

Steven Pemberton, CWI, Amsterdam; steven@cwi.nl