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About security
Our rooms have one of the most advanced key systems `Electro LIPS',
making use of keys which has a chip with a unique identification code.
It is a very flexible system as each lock can be (re)programmed to
work with any number of keys. In case a key gets lost, and might fall
in the wrong hands, the locks can simply be reprogrammed.
Each lock has its own power source consisting a pack of batteries,
and the lock starts beeping when they are getting empty, as a signal
that the batteries have to be replaced. The battery compartment is only
accessible when the door is open, so, if you ignore the beeping, the
door might one day not open at all anymore. Only brute-force will then
be left as a means to open the door.
Apparently, and you would not believe it in a building full with
educated people, this has happened several times in the past years,
as last week when the locks were serviced they turned the handle bars
inside-out.
Although this might look like a trivial thing, anybody can break in
the room within a few minutes, as now the little screw holding the
two parts of the handle bars together is on the outside. removing this
screw allows you to remove the handle bars, but what is more important
also the front plate. And once you have opened the front plate you can
remove the lock, after which the opening of the door is a triviality.
Book review
Below follows a quote from a book review by
John Mark of the book
`Take and Read: Spiritual Reading - An Annotated List' by
Eugene Peterson (Grand Rapids: Eerdmans, 1996) (author of
The Message):
Finally a quiz (answers below): - 'Brightest mind of nineteenth-
century England?
- Not everyone's favorite, but on everyone's
list?
- More influence on Western spirituality than any writer
outside the Scriptures?
- The theologian of the twentieth
century?
- Most comperhensive and penetrating of this century's
writers in the field of spirituality?
- Best introduction to the
Psalms as spirituality?
- A learned Edinburgh pastor who prayed
as much and as well as he preached?
- Best Christian account of
what actually goes on in worship?
- A brilliant essay on the
nature of holiness of time?
- A novel less about the religious
experience than a novel the reading of which is a religious
experience?
- More than half the Scriptures were written by...?
- The sanest pastoral theologian of the century?
Answers (in order):
- John Henry Newman
- 'Imitation of Christ' by Thomas a Kempis
- Pseudo-Dionysius
- Karl Barth
- von Balthasar
- Brueggemann's 'The Message of the Psalms'
- Alexander Whyte
- Annie Dillard's 'Teaching a Stone to Talk'
- Abraham Heschel's 'The Sabbath'
- Dostoyevsky's
'The Brothers Karamazov'
- poets
- Martin Thornton.
Water
Today's (electronic) campain is on informing everybody that
the University and it's campus will not have any water next
Saturday between 7 and 9 AM. I already saw several emails
and news postings about this.
Holiday effect
It is now about 10 days since we came back from our holiday trip to
China, and I can conclude now that it has been benificial to be
away for four weeks. This kind of holidays realy give you a fresh
motivation to do many (new) things. It is like a long holiday
works as an eraser, and takes away alot of negative feelings
and habbits, some of which you might not be aware any more of having.
The last days we have had clear blue skies for most of the day,
at reasonable temperatures.
One of the puzzles mentioned in the
rec.puzzle
archive is:
How many (possibly overlapping) squares are in an mxn grid? Assume that all the squares have their edges parallel to the
edges of the grid.
A solution is given by David Karr.
I wondered what would be the answer to:
How many (possibly overlapping) squares are in an mxn grid? Not
assuming that all the squares have their edges parallel to the
edges of the grid.
I think the answer is (n > m):
m
total = sum i(m - i)(n - i)
i=1
Chris Date about Relational Databases
- The relational model is the foundation of the
entire database field. Yet almost no one understands it!
The database industry seems all too willing to tolerate database
"professionals" and "experts" who are almost
completely ignorant of the foundations of their
own field.
- Now wonder, then, that such spectacular mistakes occur
in the design and/or implementation of databases, and database
applications, and database products, and database standards etc..
- Part of the problem lies, perhaps, in the all too
common misconception that if something is theoretical, it
cannot be practical (despite the fact that database management
is a multibillion-dollar industry totally founded on one great
theoretical idea!).
- Another part of the problem is, perhaps, the fact that
most relational presentations - even those by dedicated relational
advocates - quite deliberately focus on the model's intuitive
simplicity and ignore aspects and implications that might
seem esoteric or advance.
- Such an emphasis unfortunately does the cause of genuine understanding
a grave disservice.
- The fact is that the model is much deeper, and much more
robust, than most people realise.
(Taken from an seminar announcement.) This is all explained in the paper:
The Third Manifesto by Hugh Darwen and C.J. Date
(more).
The mystery of disapearing potato peeling knifes
Many years ago, when I was still living a dormitory, every year there
would be some freshman thinking he was smart, and buy four of five
potato peeling knifes, complaining that we only had one.
But all of us knew that this was a waste, because after about a week,
we would be stuck with one potato peeling knife again. Where all the other
knifes had gone, nodoby would know, but we all figured out that it
was most likely that they had been thrown away with the potato peels.
You can guess why this did not happen with the one potato knife left:
every body needed it (for other small jobs).
I woke up at 7 o' clock, which is rather early for me, but now my
sense for time seems to be disturbed. Yesterday evening, I played
a game of Go against the program
IGO
by David flotland,
which can be downloaded for free.
I have been thinking about a simple script to turn it into a
PostScript file, with each board situation
on a different
page, which should be rather compact using the right techniques.
(follow-up)
The entry page of Rain Crow
Publishers showed an interesting logo.
The `rather informal' paper
The Primary Pretenders, by
J. H. Conway, R. K. Guy,
W. A. Schneeberger and
N. J. A. Sloan, explains
why the following is an interesting number:
19568584333460072587245340037736278982017213829337604336734362294738647777395483196097971852999259921329236506842360439300
I finished the program
(which I suggested yesterday) for
converting a game record (like this)
to a PostScript file (like this).
To do this I used the following command:
go2ps <ff960909.txt >10-game.ps
In Expressions that talk about themselves the
following excersise is given:
Write a program that writes "Yes, that was me." or "Rubbish!",
if it reads its own text on a given file, or not, respectively.
I posted this to rec.puzzles
and comp.programming.contests
with the remark: Have fun!
Most mail servers have the ability to redistribute email (by sending it
to a list of email addresses), or to automatically reply to an email (by
sending it back to the originator). This makes it possible that
email start to circulate between two or more email addresses. This
is what happened just before I left. I am in a mailing list which sets
the `Reply-To:' field to itself, which means that any reply is send to
the mailing list. This is inherently wrong. About half an hour
after I had received an announcement about the
KELM'97 workshop,
I (and with me everybody else on the mailing list) received another
messages, which started of with:
VNM3043 -- MAILBOX IS FULL.
The message cannot be delivered because the
recipient's mailbox contains the maximum number of
messages, as set by the system administrator. The
recipient must delete some messages before any
other messages can be delivered.
followed by the original message. I quickly informed our helpdesk,
before I went home, wondering how many messages I would find
in my mailbox tomorrow.
(follow-up)
It stopped
Half an hour after I left the office yesterday,
there was another message starting with the same `Mail box is full' notice,
followed by the message that I had received half an hour earlier. (This message
contained the `Mail box is full' notice twice.) Luckly, through some
human intervention this was stopped, otherwise, I would have just
got an message which would contain the `Mail box is full' notice
33 times!
I wonder whether they have changed the `Reply-to:' field now. We, here in
our group, already have been thinking about just replying to this each
message with something like: Can this stop.
September
Red-brown patches have occured in the trees outside.
It is raining violently on and off.
September, when the fall sets on, is a special month.
There was a RFD posted for a nl.eternal.september.
Today, Paul van Norden, preached about
Luke 15:11-32, the story about the prodigal son, which is really
about the elder sun, and not the younger one, as he explained.
I have known Paul and his wife Yolanda since 1981, shortly after I
moved to Enschede. The past four years they have been working in
Berat "the town of a thousand windows",
Albania.
It was announced that Zuster Bouwman, a lady from our church who is in
her mid-eigthies, has become seriously ill. She already suffers from
cancer for a long time, but is seems her condition has become worse
in the past days. People from our church have volunteered to stay
with her during the night, and help her husband with the housekeeping
during the day. She might be too weak to visit her. I immediately wrote
a card to her, and send it today. I pray that God may confort her in
these days, which might well be the last days of her life here on earth.
I have never known my grandparents very well. For the day I came to know
them, I have somehow considered them as the kind of grandparents I would
like to have. They are the youngest (in spirit) old people I know,
always ready to learn more. Through them I learned that even if you
are old, life is worth living, and can be a true joy.
(follow-up)
Situation Puzzles in the News
( This is taken from a news posting to rec.puzzles posted by David Spero )
Just as I thought: that gas cap thing was too easy, mainly because it's
probably happened to everybody! But here's two much harder ones, taken
from today's media.
A Man writes an insipid novel purporting to reveal nine cosmic truths held
by an aboriginal people in South America. The writing is terrible, the
plot is silly, and the revealed wisdom almost meaningless. Yet the book
tops the best seller list for over two years, makes millions of dollars, and
starts a cottage industry of self-help based on its principles. How could
this be?
And on a much more frustrating and terrifying note:
A Central African tribal group's leaders start a movement based on killing
every single member of other tribes living in their part of the continent.
They massacre nearly a million people before fleeing across the border to
refugee camps in a neighboring dictatorship. In these camps, they rearm,
go on murderous forays into surrounding territory, and prepare to resume
their genocidal war on the country they came from. Yet international relief
agencies including the Red Cross and the UN High Commission on Refugees spend
over $1 million per day, subsidizing these camps, providing food,
health care and even jobs to the people there.
The relief agencies know what the camp leaders are doing, and have condemned
it. Yet they say they cannot move against the thugs, and they cannot stop
their massive aid program,even though everyone knows they are setting the stage
for future genocide. Why?
Scientifical evidence that intercessory prayer works
Today, I found a reference to an article with the title
Positive therapeutic effects of intercessory
prayer in a coronary care unit population, which claims
that intercessory prayer realy works.
Prinsjesdag
The third Tuesday in September is called `Prinsjesdag' (Day of the little
princes), because it is the day that our Queen (or King) rides to the
parlement in a golden carriage to read out-loud the plans of the parlement.
Today, Rolf, my former boss, flew to South-Africa
for another birding trip.
The puzzle:
A goat is tethered to the perimeter of a circular field with a rope just long
enough that he can eat grass from exactly half the area of the field. How
long is the rope?
The solution:
For a robe with lenght r, the area eaten by the goat
equals to:
r2 * acos(r/2) + acos(1-r2/2)
- r * sqrt(1-r2/4).
The length of the rope is approx. 1.15872847302.
(explaination)
Alternative puzzle:
Another farmer has a circular field. This farmer tethers his goat
outside the fence so that it
can eat an area equal to 1/2 the field. How long is the chain?
Note: as the goat moves within the tangent, the chain begins to wrap
around the outside of the fence.
(solution)
It was in the first week of August 1977 that I worked on
solving this puzzle for the first time during the holidays
together with a cousin. We did not manage to solve the
puzzle.
Alte Bekannte - Neue Gesichter (old friends - new faces) is
a photograph book by Helmut Hartwig.
When I bought this book it was wrapped in white paper, on which there was
a sticker with the following text:
Alte Bekannte - Neue Gesichter, Helmut Hartwig
Fotografische Begegnungen mit der Bahn.
Limitierte Vorzugsausgabe
Handsigniert und numeriert
ISBN 3-923937-79-2 DM 98,-
Dieses Buch trägt die Nummer 1028
When you remove the paper you see that the book is in a box,
on which it says Limitierte Vorzugsausgabe, which means that
only a limited number were printed. My copy has the number 1028
written by the author on the inside. The book also contains an
autograph of the author. On the cover of the book there two small
photographs have been clued.
As the sub-title says, the book contains photographs from old and
new trains and railroads found in Germany.
I paid 12.95 guilder for the book, which is almost one tenth of the
original price (DM 98,-) mentioned on the paper.
Collecting books
It is a long time ago, since I bought a book like the above book,
which I consider good enough to be added to my collection. For a
book to be added to my collection, it must be a work of art in
itself.
The name of the bookshop where I bought the book is
called `De Slegte', It is a bookshow which sells
books which are left over from regular bookshops (usually, because
they could not be sold anymore), and (of course) second hand books.
For this reason, the prices are usually very low.
I visit this bookshop almost every Saturday.
It has three floors,
and a small balcony between the first and second floor. The second floor
is completely dedicated to second hand books. Half of the third floor
is used for books related to computers.
De Slegte has several bookshops throughout the country. I like
their bookshop in Utrecht,
which is build inside an old house along
one of the cannals. When you think you have found the top-floor
you discover a small winding stair, which leads to some additional
floors.
One very typical thing of de Slegte bookshops is that the always
wrap your buyings in brown paper.
Calpournius Piso
Ever heard of Calpournius Piso? Me not, but read the following news posting:
Don't blame the poor believers in Piso's fairy tale. It is the Xtian
leadership who knows about the fraud and uses it to try to control the masses
that are to blame. Jesus and all the
New testament characters are all
fictional creations of a Roman named Calpournius Piso and his family. Read the
booklet The True Authorship of the New Testament by
The Abelard Reuchlin Foundation, P.O.Box 5652, Kent WA 98064
After some searching I found some a page about the alleged
piso family.
Seems some people like to make fun. I also found out that the booklet
is more than 10 years old.
Mariza Cabral posted
a puzzle about ten digits that count themself such that the i-th digit
is equal to the number of (i-1) digits in the number.
Pat Vennebush thought that this
was better stated as follows:
Make the following statement true: `In this sentence, there are __ 0's, __
1's, __ 2's, __ 3's, __ 4's, __ 5's, __ 6's, __ 7's, __ 8's and __ 9's.'
Then Mariza Cabral replied with:
`You're right, that problem is formulated more nicely, however it is a
different problem from the original one. This is because you must now
count the digits that follow the blanks, not just the digits in the
sequence that is to go in the blanks.' He also included:
`In this sentence, there are _1_ 0's, _7_ 1's, _3_ 2's, _2_ 3's, _1_ 4's,
_1_ 5's, _1_ 6's, _2_ 7's, _1_ 8's, and _1_ 9's.'
Ed Murphy told that
th problem stated by Mariza is mentioned in Martin Gardner's book
Mathematical Circus, chapter 11, problem 7, according to which the
answer is:
6210001000. For base 4 the answers are: 1210, 2020. For base 5: 21200.
And for base 6 and up: R21(0...0)1000, where R equals
base-4, and such that there are (base-7) zeroes in the parentheses.
(This is specified as unique for bases 6 through 10, but for higher bases it
merely says that this is *a* solution. The reference Gardner cites may
prove it unique, but he doesn't say so.)
Guyon Roche then wrote:
How about...
``In this sentence, there are _1_ 0's, _11_ 1's, _2_ 2's, _1_ 3's, _1_ 4's,
_1_ 5's, _1_ 6's, _1_ 7's, _1_ 8's, and _1_ 9's.''
How many solutions are there?
The answer to the last question is: there is no other answer than the one
mentioned here on this page. I verified this with a small
program.
(follow-up)
Piet Mondriaan
I bought a catalogue of an art exhibition of
the works of Piet Mondriaan
at De Slegte bookshop.
He is a Dutch painter that is especial famous for his painting consiting
of a grid of black lines, where some of the rectangles are coloured with
red, blue and yellow. The book has pictures of most of his paintings, and
a short biography of the most important events in his life, sorted by date.
At the moment it is a few minutes after three o' clock in the afternoon
(local time, of course). I am in the middle of some heavy coding, which
calls for a short break. What follows is a list of things that caught
my attention in the past day:
This morning, while playing with Annabel, so that
Li-Xia could dress
her, I still found myself thinking about the fact that the Julia
set of the cauliflower fractal can be described
by infinite sets of equations. In a sense it is not so strange that
I was thinking about it, because it has been on my mind, since
yesterday evening when I listened to a talk about chaos and fractals.
But what was strange, is that I was thinking about something of which I am
sure Annabel does not have the faintest idea that it might exist. Of course,
her perception of the world is so different than mine, but I am not sure
that she will ever understand these thoughts when she has grown-up.
Fred Galvin wrote:
`This puzzle goes by the name
logic/self.ref in the rec.puzzles
archive.
For more information (bibliography, generalizations, and a simpler proof
than the one in the archive) see the letters to the editor (by Steven
Kahan, Lee Sallows, and somebody by the name of Fred "Gavin") on pp.
276-277 of Mathematics Magazine, vol. 66, no. 4, October 1993.
Mid-autumn festival is coming
May I wish you:
Dm mmDm Dm Dm Dm m mmmDm
m DD m ""Dm DD m DD mmDDmmDm DD""D"
DD"""DD"""DD" mmmDDmDm DD mD" mDDDm DD DD DD DD
DD DD DD mDDm DDDD"" D"DD " DD DD mmDDmmDDmmDm
DDmmmDDmmmDD mDDD"D" DDm DD """DD""""" m DD m "
DD " m" DD D" Dm DD DD"Dm DD" DD Dm
DD DD mD" "Dm DD DD DDm mD" m DD "Dm
D" D"m" "D" D"m"" "D" " "D" "
(I received this from Zhu Zhiting, East China Normal University)
Tail tail division
void main(int c,char*v[]){int d,a;if(c<3)return;a=atoi
(v[2]);for(d=strlen(v[1]);d<strlen(v[2]);d++)a*=10;d=
atoi(v[1]);for(;;c=d/a,printf("%d",c),d=(d-c*a)*10+c);}
The Universe
I had a look at a picture taken by the Hubble telescope.
I just talked with Annabel on the phone. This was the first time that
she was talking back, not that it made much sense, but she really replied
to what I said.
Today, we heared that zuster Bouwman passed away yesterday. She is save with
the Lord Jesus now, as she firmly
believed. In the past two weeks she has
suffered greatly, but she witnessed that there was always a joy in her heart
that no one could take away from her. She now has ran her race, and come to
the finish of her life.
But still it is a great lost, in the first place for her husband, broeder
Bouwman, for whom it must be difficult to continue on his own in his high
age. We pray for him. But also for our church this is a great lost. I will
miss her. A date for the funeral has not been set. I very much would like
to attend the funeral.
(About the date of her funeral.
Follow-up)
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