This is the web page of Richard Parkins, last updated 3 June 2022.
If it has not been updated for a long time, I may be no longer active.
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This is what I look like.
55 years ago I first used Occam's Razor. Since
then I have used no other.
This web page is still under construction, so there may be more of it next time
you look: I try to remember to change the last updated date at the top of this
page whenever I change anything.
Opening screw top jars
I've seen lots of reviews of grocery products recently complaining about the difficulty of opening screw top jars. This little trick may help. Slip the handle end of a spoon or a wide screwdriver under the edge of the lid, as in this picture.
Now lever the the lid gently away from the glass. Don't push too hard or
you will crack the glass. You may have to try several places around the lid.
Eventually you will hear a hiss as the air gets in to fill the partial vacuum
inside which is holding the lid down. Then it will be much easier to unscrew the lid. I've successfully used this trick for many years.
If you suffer from tinnitus ("ringing in the ears"),
this page may help you.
I have lived and worked in Scotland, Belgium, Switzerland, and the USA as well
as England. Currently I live in Cambridge, England. If you have good reason to
need my full address ask at the email below.
I design and make things. For almost all of my working life, I designed and
made computer software, but I have retired from paid work.
For a brief (and currently incomplete) history of my working life
I still work on my own, mostly open-source, projects.
Currently I'm working on an open-source editor for sqlite databases. It is an
improved version of sqliteman, and you can download the source code or a built
version for Linux
at this github page.
I'm also working on an Android application which generalises the idea
(supported by several currently available apps) of muting your phone's ringer
while your calendar says you have some sort of active event, such as a meeting.
My version allows you to set up classes of calendar events and cause
your phone to take different types of action according to the class of the
currently active event. You can find it
at this github page.
Other possibly useful repositories on github are:-
I have always been interested in Mathematics
(for an early maths adventure see here)
and I studied Mathematics at Trinity College, Cambridge.
However I defected to computers and made my career in that area.
I am a collector of puzzles and I also design and make puzzles of various
kinds. This movie shows one of my puzzles disassembling
and then reassembling itself. If you want to buy one, it is available on the
at this web site.
Here are three more of my puzzles.
They are all available to buy on another web site
I also both collect and make puzzle rings: here is a composite picture of a
puzzle ring that I designed and made, in the folded and unfolded states.
The configuration is called Borromean Rings
after the Italian family of Borromeo, who used it as a
family emblem (on another web site).
The three rings are linked, but if you delete one ring, the others are not
linked. The puzzle was originally designed (many years ago) as a result of a
discussion which started from the (bought) puzzle rings which I owned at the
time. Someone wondered if it was possible to make a puzzle ring with this
linkage, so I went home, designed it, and made one. The gold one illustrated is
one that I made more recently, after the restrictions on people owning gold
bullion were removed.
If you live in, or visit, Cambridge, you can see some sculptures with the same linkage outside the Isaac Newton Institute for Mathematical Sciences in Clarkson Road.
A generalisation of this linkage to more than three rings is called a
Brunnian Link. This is a set of loops which are linked, but if any
single loop is removed, the others are not linked. For any number n
3 or greater, there exist (infinitely many distinct) Brunnian links with
n loops. One possible link looks like a chain: below is a picture
of one on a young lady's wrist - thanks to Leyla for modelling it.
If you want such a bracelet, or a necklace with more loops, you can buy the
loops on the Internet at this web site.
shows how to assemble the links into a chain.
This is another piece of puzzle jewellery, in this case a bangle.
The two pieces slide together as in this movie.
Once you put it on your wrist, the two pieces cannot come apart because your
wrist is in the way. You can also buy this one on the Internet
at this web site.
This movie shows another
puzzle bangle sliding together. This one uses a bidirectional sliding system
to make it fit snugly on the wearer's wrist. You can buy one
This more recent ring design also has three loops, but a different topology.
In this case each loop is linked to the others so that the three of them form
a closed chain. There is more than one way of doing this: the commonly seen
ring with three gold loops of different colours of gold is also a closed chain,
but not the same linkage.
I also have puzzle rings with closed chains of four and five links. Somewhere
I think I have a design for one with six links, but I have not got round to
making that one. Incidentally the well-known "Turkish" puzzle ring is also a
closed chain of four links, but again my design is a different linkage.
I put "Turkish" in quotes because my researches suggest that the design
actually originated in Latin America. I have several rings of the "Turkish"
design, mostly with some or all of the individual wires replaced by
two or three parallel ones.
The almost certainly false story is that
the design was used as a Turkish wedding ring. If the wife wanted to have an
adulterous affair, she would take off her wedding ring and not be able to put
it together again (a very sexist assumption), and so the husband would find out.
There is of course another very sexist assumption here that a married woman
might want to have an adulterous affair, but she needs to take off her
wedding ring because otherwise a Turkish man would see the wedding ring
and not want to have an affair with a married woman.
Islamic law (and indeed Jewish law in biblical times) does not require married
men to be faithful to their wives. The normal English translation of the
in the original Hebrew) as "Thou shalt not commit adultery" is really
incorrect since adultery in English includes an affair between a married
man and a woman who is not his wife, and the Hebrew word does not include
that meaning: only an affair between a married woman and a man who is not her
husband is forbidden. Yes, that's sexist too, but don't blame me, I didn't
write it: I'm just clarifying the originally intended meaning.
I don't sell puzzle rings: it's too much work to make them compared with what I could reasonably charge. If you are a jeweller and you are interested in making my puzzle ring designs under licence, please get in touch.
A piece of mathematical jewellery (but not a puzzle) which I do sell is
this earring or pendant
which is based on a three-dimensional space-filling curve. You can buy it
at this web site.
For some of my earlier writings on two-dimensional space-filling curves
see the references below.
This is a coffee table with a glass top and a hollow space underneath which I designed and made to display some of my collection of puzzles. For a discussion
about how I came to make it, see
As a puzzlist I am of course interested in Rubik Cubes. I own Rubik cubes of
sizes 2, 3, 4, 5, 6, 7, and 8. I have solved sizes 3, 4, and 5, although I seem
to have lost the order 5 solution, and it was too complicated to remember. The
order 2 one is too easy to bother with a formal solution. One problem with real
Rubik cubes is that once you get it out of the standard position, it is hard to
keep track of what you are doing. For this reason I made a virtual one. If you
have FreeCAD on your computer, or are willing to download it, you can play with
my virtual one. It is a
FreeCAD (see the website) macro and you can find it
at this web site.
There is a similar puzzle called the
Megaminx (wikipedia entry)
based on the regular dodecahedron: it has twelve faces each a different colour rather than six. I also made a FreeCAD macro with a virtual version of that, which you can find
at this web site.
Like some other puzzlists, I also think about physical problems in the real world. Many years ago I was making a cup of coffee, and I had poured the coffee into the cup and was about to add the milk when the doorbell rang. The question that I thought of was whether I should add the milk before answering the doorbell or afterwards. The utility function (what I wanted to maximise) was the temperature of the coffee and milk mixture by the time I got to drink it. Microwave ovens had not been invented by then, so if it took too long to deal with whoever was at the door and the coffee got too cold, the only choice was to throw it away and make a fresh one.
It took me about 30 years to get around to writing down the equations and solving this problem. Later I realised that there is a simple solution which does not require any equations at all. I encourage you to try and solve it for yourself before looking at the answer
I cam also interested in word puzzles. If you want to crack your brains a bit,
try to find five eight-letter English words which are anagrams of each other
(made of the same eight letters in different orders). They are all reasonably
common words. Another word puzzle of mine is to find pairs of words which are
spelled the same but pronounced differently and etymologically unrelated. The
etymologically unrelated condition is needed to exclude words such as contract where the noun is pronounced differently from the verb.
I know of three such pairs, although only one pair are really common words,
and one of the others doesn't work in American English where the two are
pronounced the same. I'm not giving solutions here.
Another of my interests is the ambiguity of the English language, a major issue for AI researchers trying to write software to understand English. Some examples that have amused me are
I also used to be a regular Arena promenader. Unfortunately the travelling and
queueing got too much for me and nowadays I go only occasionally and usually
sit in the stalls. At this web site
is a picture of me dressed up for the Last Night of the Proms in 2005.
There is another photograph of me queueing for the Last Night in 1998 on the front cover of Classical Music dated 4th September 1999: I can't reproduce it here for copyright reasons. I still go to concerts in Cambridge as well.
This bread machine
story amused some of my friends when I told it to them: it may amuse you
If you have ever wondered at the remarkable coincidence that we live on a planet with a moon just exactly the right angular diameter to eclipse our sun [in fact it is so exactly right that we have both total and annular eclipses], here is my theory about why it less surprising than it otherwise appears to be.
I am also interested in politics (who isn't). In a referendum on 5th May 2011, the British
electorate rejected the alternative vote system, which isn't truly proportional
anyway. I thought about it and devised a truly proportional system which
preserves the link between MP and constituency, which British voters (rightly)
consider important. You can read my thoughts about it
I also like to bake.
is my shortbread recipe.
You can contact me by email at "aleph0hpela-bew19 yahoo co uk" with the obvious
(at least to humans) insertions. I'm sorry not to give an address that you can
just copy and paste, but I do not want it harvested and used by spambots. If
nevertheless I get too much spam on it, I will change it, so if emails to me
suddenly start failing, look again at this web page to see what the email
address has changed to.