## Fr. Magnus Wenninger, O.S.B., IV

Last week I ended with a remembrance of my wonderful visits to see Magnus at St. John’s Abbey in Collegeville, MN.  These were certainly unique among my visits with other friends and mathematicians.

I left off with an excerpt from 10 June 1994; this next one is dated 18 June 1994.

This is another excerpt describing elements of our collaboration together; I point your attention to the first few sentences, where “stellations of two cores” are mentioned.  Again, since the focus is on my work with Magnus, I will elaborate a bit on this idea without giving all the necessary background.  (If you’re really curious, the internet has all the answers to your questions about stellations.)

Consider the following uniform polyhedron, called the stellated truncated hexahedron.

This name is perhaps a misnomer, since careful observation reveals that the octahedron bounded by the eight pink triangles in fact lies entirely inside the cube (hexahedron) bounded by the eight octagrams.  So the octahedron does not actually truncate the cube.

Here is a partial figure from a paper I’m currently writing based on the notes referred to in the above excerpt.

Notice in d) how the red square truncates the black square to create a regular octagon.  So this figure shows how the lines containing the edges of an octagon (analogous to faces of polyhedra in three dimensions) divide the plane into different regions.

But in h), we have a figure bounded by lines containing edges of two squares, but one lies entirely within the other.  So we cannot choose a single polygon as generating this diagram.  Therefore, we say this figure is generated by two cores — the two squares which do not intersect each other.

Of course there are many other polyhedra which may be thought of in this way, but hopefully these two examples illustrate this polyhedral thread in my collaboration with Magnus.

This excerpt is from November 1994.  I include it as it illustrates how industrious Magnus was in building polyhedra.  He would build polyhedron models and sell them at craft fairs to raise money for the Abbey or other related causes.

“Sales average only about a dollar an hour for my work.”  Now 1994 was not all that long ago…a dollar an hour hardly seems fair for the work of a world-renowned model builder!  But most people just see a few brightly colored bits of paper held together with a few drops of glue, and have no real idea about the mathematics behind the models or what it takes to build them.

So building polyhedra really was a labor of love for Magnus; he would have built them just to give them away.  I recall one trip where I brought back three large trash bags filled with models which Magnus built but had no room to store.  I kept some for myself, but then freely distributed them to mathematics teachers and students of all levels so they could take pleasure in holding and studying them.  I hope some were inspired to build a few models on their own….

Again, Magnus stayed rather busy!  Note that in 1995, he had already been a priest for 50 years.  Also notice the reference to the ISIS Congress in Washington, D.C.  Magnus wrote a fairly detailed “memoir” about his attendance at that conference.  I’ll show you several excerpts from that memoir in next week’s post, as it comes rather later in the year (and so there isn’t room for those excerpts this week).

This is another example of a figure Magnus sent me as part of our ongoing collaboration.  At the beginning of our correspondence, I had begun a textbook on polyhedra based on spherical trigonometry, which I used for a course I taught at the college level.

In particular, I was investigating the mathematics in Spherical Models.  Recall that I wasn’t satisfied with numerical approximations — I wanted exact mathematical expressions for the angles used to build geodesic models based on polyhedra.

The above figure is based on one I used for designing spherical models where some of the faces of the polyhedron are pentagons.  When projected onto a sphere, you needed to draw geodesics (great circles) connecting the vertices and calculate the individual segments in the spherical pentagram just created.

Now in the plane, when you join the vertices of a pentagon with diagonals, the diagonals are subdivided into the ratio φ : 1 : φ, where φ is the golden ratio.  But the angles into which the diagonals of the spherical pentagram are subdivided isn’t a matter of calculating a simple ratio — there is a lot of trigonometry involved.  Moreover, the ratio varies with the size of the original spherical pentagon.

In any case, here it not the place to discuss all the mathematical details.  I just wanted to illustrate again one aspect of my correspondence with Magnus.  I feel certain I must have sent him all my draft chapters, but likely he gave me his commentary when I visited, or perhaps somewhere in those emails that have been lost forever in some virtual black hole….

This last excerpt shows Magnus’ gentle nature.  Perhaps you are not aware of the difference between the geometrical terms trapezoid and trapezium (see this article for a brief history) — but the meanings in the UK and US are swapped.  What is a trapezoid here is a trapezium in the UK, and vice versa.

In any case, I made a reference to “Those crazy Brits!” when discussing this difference in nomenclature, and Magnus was sympathetic to their cause, as shown in the last few sentences of the excerpt.  I can honestly say I cannot recall him ever saying a disparaging word about anyone (try counting the number of people you can say that about).  He was always keen to understand all sides of an issue — and this always made philosophical and theological discussions so interesting.

I’ll stop with this comment today.  Next week, we’ll begin by looking at Magnus’ memoir on the ISIS conference in Washington, D.C.

## Fr. Magnus Wenninger, O.S.B., III

I just returned yesterday from the Joint Mathematics Meetings in San Diego, where I gave my talk commemorating Fr. Magnus Wenninger.  Last week, I posted several excerpts from my correspondence with Magnus which I included in that talk.  Today, I’ll continue that discussion, again adding commentary as appropriate.

I included this quote because of Magnus’ translation of Kepler:  “Beyond doubt there exists in the mind of God the eternal form of all these shapes, which we call its truth.”  Magnus had a very philosophical approach to mathematics, and always considered that his work was some manifestation of the Divine.

Is mathematics invented or discovered?  This age-old and unresolved question has sparked much debate over the centuries.  But for Magnus, the answer is clear:  mathematics is discovered.  The polyhedra he created all existed in the mind of God long before he reimagined them with a few pieces of paper and a little glue.

So Magnus’ vocation as a Benedictine monk strongly influenced how he thought about his life’s work.  Having personally held and studied some of Magnus’ models, it is not a stretch to say that perhaps they were in fact touched by the Divine….

This excerpt again shows how very active Magnus was during the 1990s.  But this particular letter is part of a thread in our correspondence where I was planning my first visit to see Magnus.

What made the trip a little more challenging is that I also wanted to visit Peter Messer in Wisconsin as well.  Magnus introduced me to Peter as someone very interested in studying stellations of polyhedra, both from concrete and abstract viewpoints.  (I also have a folder of correspondence from Peter, but that for another time!)  Also, Peter was using Mathematica, which I was quite familiar with.  So it seemed appropriate that we should meet.

Peter just recently retired, but was a dermatologist at the time, and hence had a busy professional schedule.  So I was trying to juggle three schedules to arrange a series of visits — all through written correspondence!  Now we would consider this approach somewhat anachronistic, but at the time, it was perfectly reasonable.

The title of my talk at the Joint Mathematics Meetings was Working with Magnus Wenninger.  So in addition to excerpts which documented our getting to know each other, I also included excerpts which illustrated various aspects of our collaboration.

If you look back at the very first excerpt from last week’s post, you’ll notice the second paragraph begins “I’m in no hurry to get information about barycentric coordinates.”  In my introductory letter to Magnus, I mentioned that I had begun work on finding coordinates of polyhedra using a barycentric coordinate system.

But over the next several months, I did send Magnus notes on barycentric coordinates, and he did study them.  Now is not the time to go into a detailed discussion of barycentric coordinates — the point is that Magnus occasionally included diagrams in his correspondence to present his perspective on different aspects of our collaboration.

The first figure shows barycentric coordinates relative to a six-frequency triangle.  The second figure shows how he would use this abstract idea to create a template which he would use to make what would be called a six-frequency geodesic icosahedron.  Again, now is not the time to go into details, but I did want to include a brief description for those who are a little more familiar with polyhedra and geodesic structures.

Although, as I mentioned just a few moments ago, I began arranging my first visit with Magnus through letters, I must have finalized arrangements with him and Peter over the telephone.  This excerpt from 10 June 1994 was the first letter since February which mentioned my visit; I must have realized that calling both Magnus and Peter was ultimately more efficient than writing them.  I should mention that Magnus had difficulty hearing over the phone, and so we never had any substantial conversations on the telephone; our chats were confined to arranging logistics of visits or other such details.

I always enjoyed my visits with Magnus.  I would stay in a guest room in the Abbey at St. John’s University in Collegeville, Minnesota — this was a spartan room with a simple bed, a small desk and chair, and I think maybe another chair to sit in…it’s been too many years to remember the exact details.

I’ll recall a typical day during one of our visits — although the individual visits tend to blur together.  I’d say I made a half-dozen visits while I lived in the Midwest, including a time when Magnus visited me and I drove him to a conference at the University of Illinois Urbana-Champaign.

In any case, there was a common room for guests in the abbey for breakfast.  Nothing too elaborate, but enough to get you going.  I’d be on my own in the morning — working on polyhedral pursuits, or perhaps just walking around the beautiful campus.  My visits were usually during the summer, so I was spared the cold of Minnesota winters.

Magnus would then find me around lunchtime.  He had permission for me to have lunch and dinner with the other monks — a real treat, since this was not the usual protocol.  But Magnus and I often had philosophical and theological discussions as well as conversations about polyhedra, and so I was welcome at meals.  I can’t remember details, but the conversations were always quite stimulating.  The Benedictines at St. John’s were rather liberal.

In the afternoon, we’d meet to discuss various aspects of polyhedra or perhaps work on some models.  Often Magnus would be building while we talked.

Then I’d be on my own for a bit.  Often I would go to one of the Offices in the Abbey church before dinner, and I’d meet Magnus after the service (the monks sat in their own section) and we’d walk down to dinner and more interesting conversation.

Our evening sessions were a bit more informal, and our discussions would often be more philosophical rather than polyhedral in nature.  Magnus would have his nightly brandy — or perhaps a little Grand Marnier, since I would usually bring him a bottle when I visited.

Then it was early to bed for Magnus, although I was up a little later.  I am not sure when the first Office was in the morning, but I am fairly certain I was always in bed at the time….

We must have made arrangements for future visits either by phone or email, since this is the only correspondence I have which includes any details of visits with Magnus.  But they were wonderful times which I shall always remember fondly.

I’ll continue with excerpts from my correspondence with Magnus next week…so stay tuned!

## Fr. Magnus Wenninger, O.S.B., II

In this next installment of my commemoration of Fr. Magnus Wenninger, I’ll excerpt various snippets from our correspondence together which illustrate Magnus’ unique perspective as well as highlight our collaboration together.

This is by no means meant to be a complete biography of Magnus’ life; rather, I hope you get to know Magnus a little through our particular correspondence.  Of course everyone who knew Magnus had a slightly different experience.

I have about 65 letters in my folder of correspondence, which includes both letters from Magnus and my replies.  I had to be selective in preparing my talk for the Joint Mathematics Meetings, and what follows are the excerpts I chose (in chronological order), along with some personal commentary.

I chose this excerpt for a few reasons.  First, Tom Banchoff will also be giving a talk at the JMM in our session commemorating Magnus.  But I also wanted to highlight the fact that Magnus, although already in his early seventies, was still very active.  He was routinely invited to give talks and presentations, and also published papers occasionally.

And, as he indicated, when not otherwise occupied, he was always building models of one sort or another.  And I really do mean always — even at conferences, he would often have a table set up where he would build models and discuss polyhedra with anyone interested enough to stop by and see what he was up to.  Which was usually very many people….

This excerpt is from a letter dated 30 August 1993.  It would take too long to set the stage for what this letter discusses, but I want to draw attention to the words “eye-balling” and “guessing” here.

Magnus’ focus was on building models, not on studying their precise mathematical properties.  So if he didn’t actually know exact coordinates for a model, he would approximate, and build what he called a variation of the abstract mathematical model.

But here, Magnus is being somewhat humble — for his eye-balling and guessing is scaffolded on decades of model-building experience.  It’s like giving a chef who graduated from Le Cordon Bleu a bowl of soup, say, and asking him or her to “guess” what spices were used.  You’d get a lot more than just a guess….

This intuition about three-dimensional geometry was absolutely key to Magnus’ model-building success.  If a spike on a model was too “pointy,” Magnus would simply design a variation with the features he wanted.  And somehow, almost magically, they always turned out wonderfully.

This next excerpt is dated 13 September 1993.  The important quote here is the last complete sentence.  As I mentioned last week, Magnus is best known for his trio of books Polyhedron Models, Spherical Models, and Dual Models.

Magnus is not the first to have enumerated all the uniform polyhedra; this had been done by a few others earlier — Coxeter (et al.) published a complete enumeration in 1954, Sopov proved completeness of the list in 1970, and Magnus’ Polyhedron Models was published in 1971.

And even though Polyhedron Models was always the most popular of the three books, Magnus’ felt that Dual Models was more significant since it was the first time all the duals of the uniform polyhedra were published.

I also note his use of words:  “more significant.”  I don’t think Magnus would never had said “I am more proud of Dual Models.”  He was not a prideful man, always giving credit to his God for his insights and abilities.

But I think significance here is all relative.  In terms of popularizing polyhedra and model building, Polyhedron Models was certainly the most significant of the three books. But in terms of a contribution to the mathematics of polyhedral geometry, I would agree with Magnus that Dual Models was the most significant of the three.

Of course Spherical Models is quite wonderful, too….  But in this book, Magnus indicated how to build (or approximately build) a wide variety of spherical models.  However, moving in this direction is much more difficult mathematically and in some sense broader than just considering the uniform polyhedra or their duals, since there are many ways to build a spherical model based on a given polyhedron.  So there would be little hope of being so comprehensive when discussing spherical models.

I include this next excerpt since it is one of the few times Magnus has mentioned his own abilities in his letters — it also echoes the excerpt from 30 August 1993.  So there is little more to say here, except to note that he mentions his intuitive abilities are derived from building over a thousand models, not to any inherent ability.  Again, an instance of his humility.

In this excerpt, I point to the phrase, “…holding a real model in my hands is still my greatest thrill.”  Those of us who knew Magnus absolutely knew he felt this way about model building.

Because of his extensive polyhedral network, he had connections with mathematicians who helped him with precise, computer-generated diagrams to help him make models for his books.  But he was less interested in the details of how the diagrams were made than he was in diving right into building the models themselves.

He was also well aware that computer graphics were an excellent tool which could be used to discover new and wonderful polyhedra — changing a parameter here or there would result in a different polyhedron, and it is easy to look at parameterized series of polyhedra with a computer.

But, this was all in aid of model building, not an end in itself for Magnus.  There are plenty of others who focus on the computer graphics — as it should be, since any polyhedral enthusiast will have their own particular areas of interest and expertise.

Only five excerpts, and it’s time to finish!  I didn’t realize I had so much to say about these snippets of correspondence.  But I hope you are beginning to have some insight into who Magnus was and what he accomplished.  I’ll have still more to say as in the next installment of excerpts from my correspondence with Magnus.

## Fr. Magnus Wenninger, O.S.B., I

Fr. Magnus Wenninger was an astoundingly prolific polyhedron model builder, having built many thousands of models during his life.  He is best known for his trio of model-building books:  Polyhedron Models, Spherical Models, and Dual Models.  Ask anyone who is an enthusiastic model builder, and I will bet that they own at least one, if not all three.

These books were important because they opened up the world of polyhedron model building to a much wider audience, giving detailed instructions on how to build dozens of models, as well as discussing the mathematics underlying polyhedra (although to a limited extent).

But perhaps equal to Fr. Wenninger’s model-building capabilities was his ability to connect polyhedron enthusiasts with one another.  Because of his books, other model builders would correspond with him describing their particular interests, and he would connect them with others who had written to him with similar interests.  In 1996, he created a mailing list where those interested could exchange ideas about all aspects of polyhedra.  It was very active for several years, but because of the proliferation of sites about polyhedra in recent years, it is somewhat less so now.  It is now maintained by Dr. Roman Mäder.

I was first introduced to Fr. Wenninger’s books by finding them among the stacks at the mathematics and science library at Carnegie Mellon.  I don’t recall how many times I checked out Polyhedron Models; I was completely engrossed.  I would page back and forth, over and over, looking for similarities between the various models and underlying geometrical patterns.

I began corresponding with Magnus in the summer of 1993.  I still have all of our correspondence — I made sure to photocopy any letter I sent him so I would have a continuous record of our polyhedral conversations.

Sadly, Magnus Wenninger passed away last February at the age of 97.  When I heard about this, I thought it would be fitting to organize an Invited Paper Session at the Joint Mathematics Meetings (on 12 January 2018 in San Diego) in his honor.  I invited some of his colleagues from the polyhedron mailing list, and others as well.

This morning, I began reading through the letters exchanged with Magnus in preparation for a talk I will be giving in the session.  Yes, this was in the day when people wrote letters, and moreover, wrote them by hand.  Amazing!  Such an interesting treasure trove of ideas and thoughts.

For my talk, I am excerpting text from Magnus’ letters to me, taking pictures of the text, and using these excerpts as the main body of slides.  I am not sure how many others had an extensive correspondence with Magnus, but I thought this would provide a unique glimpse into Magnus’ life.

And so begins this series of posts commemorating Fr. Magnus Wenninger.  I’ll continue this post by giving an overview of our relationship.  Then later, I’ll share with you some excerpts from his letters to me, as well as provide commentary when appropriate.  It is fitting that he should be remembered; organizing the Invited Paper Session in his memory as well as writing about him in my blog will serve as my contribution.

I was simply fascinated by the beauty, intricacy — and to an extent, simplicity — of three-dimensional polyhedron models.  But I was also a graduate student at Carnegie Mellon in mathematics, which was not insignificant.

And just what was the significance of being a graduate student?  Well, I was being trained to think rigorously, mathematically.  At the time, however, all the accessible books on polyhedral geometry were at a relatively elementary level.

What I mean is this.  When you study a polyhedron, there are many metrical features evident, such as edge lengths and various angles; for example, the angles between two faces of a polyhedron (like the 90° angles between faces of a cube).  And in many of these books, these lengths and angles were given — but in most cases, only in tables with approximations to enough significant figures necessary to build reasonably accurate models.

I started to wonder how all those numbers were calculated.  I wasn’t satisfied with approximate results; I wanted exact results.  Thus began my polyhedral self-education, some thirty years ago.

So I began playing around, and when I finished graduate school, mustered up the courage to write Magnus.  I was rather intimidated at the time — I had just started learning about polyhedra, and he had published at least three books on the subject!  But it turns out Magnus was unusually generous with his time and talent, and replied within a few weeks.

My introductory letter was dated 5 July 1993, and the last letter I have from Magnus bears the date 22 October 1997.  I am quite sure that this is because we continued our correspondence online.  However, virtually all of that correspondence is lost, since most of  it was conducted through a university email address I no longer have access to.

There are a few lingering emails in my gmail account, since my correspondence with Magnus waned after I left my first university position.  But in addition to maintaining an active correspondence with Magnus, I did visit him a number of times at St. John’s Abbey in Collegeville, MN.  I would stay in a guest room at the Abbey, and join Magnus for lunch and dinner.  Throughout the day, I would visit Magnus’ room where we would talk about polyhedra, or perhaps I would work on my own, or just take a walk around the campus.

My interactions with Magnus were absolutely inspirational.  Looking back at notes from those years, I am amazed at how much I accomplished — and this at a time when computer graphics were much less sophisticated than they are now.  I would often share results with Magnus in my letters, and he would provide his unique perspective on my current work.  Even when he was critical, he was unfailingly kind.

So in my next post, I’ll begin sharing excerpts from Magnus’ letters to me.  That is, after all, how you get to know a person — one interaction at a time.  Hopefully you will be able to get a sense of the humble, brilliant, generous man Magnus was and continues to be for those who knew him well.  His legacy lives on through us, as we strive to be for others who Magnus was for us.

## Beguiling Games IV: Scruffle.

We’ll start this installment of Beguiling Games by discussing who has a winning strategy in Splotch!  Recall the rules of the game:  players alternately color in squares in a 4 x 4 grid, with the goal of creating a specified splotch, shown below.  The splotch may be rotated and/or reflected as well.

For a more complete description together with an example of how the game is played, you can look at the previous installment of Beguiling Games.

OK, now for the solution!  It turns out that the second player can always win.  Let’s see how.  I found it easiest to think about a strategy by imagining the grid as being divided into quadrants, like this:

Now here is the important observation:  the first player who fills in a second square in any of the quadrants loses, regardless of whether the squares are adjacent or diagonally situated.  Of course there are other ways to lose, too — as with all these two-player games, there are multiple ways to analyze them.

So let’s get specific.  Suppose the first player colors in square A1 (see the figure below).  The second player then colors in the square labelled B1.

At this point, the red squares indicate all the places the first player cannot play without losing the next turn.  So the first player must color in one of the two empty squares, after which the second player will color in the other one.  So after two turns for each player, the board now looks like this:

So no matter what square the first player colors in next, one of the quadrants will contain two filled-in squares, and so the second player will win on the next move.

A similar strategy may be used no matter where the first player begins.  Consider the first few moves in the following game.  The first player colors in the square A1, and the second player colors in B1.

Again, the first player must avoid the red squares, or else the second player would win on the next turn.  Whichever square the first player colors in next, the second player can always play “two away.”  The result will be 1) the first player will not be able to win on the next turn, and 2) one square in every quadrant will be colored in.  This means that the first player is forced to put a second square in one of the quadrants on the next move, meaning that the second player will win on the turn after that.

This is the simplest strategy I found for the second player.  I would be happy to hear if some reader found an even simpler way to describe a winning strategy!

What about using other splotches?  If the splotch contains too many squares, it is possible to force a draw.  For example, given the splotch below, either player may force a draw simply by coloring in the four corners on their first four moves.

Interestingly, it is difficult to come up with a splotch where the first player has a winning strategy (other than a splotch which is just a single square, of course).  The more squares included in the splotch, the more difficult the analysis.  But for simpler splotches, it seems a clever division of the board allows the second player to win.

For example, consider the following square splotch.

Now divide the board into the following 2 x 1 regions, or dominoes:

Player two has a simple winning strategy.  Whenever the first player fills in a square, the second player fills in the other square of the domino.  It should be clear that the second player can never lose this way.  The first player will eventually have to fill in a square directly above or below a filled-in domino, and when this happens, the second player wins on the next move.

A complete analysis of Splotch! is likely beyond reach.  Just counting the number of possible splotches (up to rotation and reflection) would be a challenging task unless you wrote a computer program to exhaustively find them.  Without rotations and reflections, there are 216 = 65,536 possible subsets of 16 squares, and hence 65,535 splotches (since a splotch must include at least one square).  So a computer program would be able to find them all relatively quickly.  The interested reader is welcome to undertake such a task….

Here is another simple two-player game for you to think about, which I call Scruffle.  It is played on a typical 3 x 3 Tic-Tac-Toe grid.  Players alternate playing either a 1, 2, or 3 anywhere in the grid.  A player wins when a number they place creates a column, row, or diagonal which contains a 1, 2, and 3 in any order.

There is one additional constraint:  only three of each number may be placed in the grid.  So once three 1’s (for example) are placed in the grid, no player may place another 1 anywhere in the grid.  This is not an arbitrary constraint — you can show that the game cannot end in a draw with this condition.  See if you can show this!

For the first puzzle, show that the first player has a winning strategy.  This is not difficult; the simplest strategy I found involves the first player’s second turn involving playing the same number they played on the first turn.

A slightly more challenging puzzle is to require the first player to play a different number than the number they played on their first move.  Does the first player still have a winning strategy?  I’ll give you the solution in the next installment of Beguiling Games!

## Bay Area Mathematical Artists, IV.

We had our last meeting of the Bay Area Mathematical Artists in 2017 this weekend!  We had a somewhat lower turnout than usual since we’re moving into the holiday season.  But it really wasn’t possible to move the seminar a week earlier, since many of us affiliated with universities were in the middle of Final Exams.

As we had been doing before, we began with a social half hour while waiting for everyone to show up.  We then moved on to the more formal part of the afternoon.

There were three speakers originally slated to give presentations, but one had to cancel due to illness.  Still, we had two very interesting talks.

The first talk, Squircular Calculations, was given by Chamberlain Fong.  Chamberlain did speak at the inaugural September meeting, but wanted a chance to practice a new talk he will be giving at the Joint Mathematics Meetings in San Diego this upcoming January.

So what is a squircle?  Let’s start with a well-known family of curves parameterized by p > 0:

$|x|^p+|y|^p=1.$

When p = 2, this gives the usual equation for a circle of radius 1 centered at the origin.  As p increases, this curve more and more closely approaches a square, and it is often said that “p = ∞” is in fact a square.

However, in Chamberlain’s opinion, the algebra becomes a bit unwieldy with this way of moving from a circle to a square.  He prefers the following parameterization:

$x^2+y^2-s^2x^2y^2=1,$

where s = 0 gives a circle, and the central portion of the curve when s = 1 is a square.  As s varies continuously from 0 to 1, the central portion of this curve continuously transforms from a circle to a square.  This parameterization was created by Manuel Fernandez Guasti; you can read his original paper here.

Chamberlain’s talk was about extending this idea in various ways into three dimensions.  He showed images of squircular cylinders, squircular cones, etc., and also gave equations in three-dimensional Cartesian coordinates for all these surfaces.  You can see some of the images in the title page of his presentation above.  It was quite fascinating, and there were lots of questions for Chamberlain when his talk was finished.  Feel free to email him at chamb3rlain@yahoo.com if you have further questions about squircles.

The second talk was given by Dan Bach (also a speaker at our inaugural meeting), entitled Making Curfaces with Mathematica.  Yes, “curfaces,” not “surfaces”!

Dan took us through a tour of his very extensive library of Mathematica-generated images.  He is fond of describing curves using parameters, and then changing the parameters over and over again to generate new images.

This is easy to do in Mathematica using the “Manipulate” command; below is a screen shot from Mathematica’s online documentation showing an example.

The parameter n is used in plotting a simple sine function — as you move the slider, the graph changes dynamically.  Note that any numerical parameter may be experimented with in this way.  Simply make a slider and watch how your image changes with the varying parameter.

So what are “curfaces”?  Dan uses the term for images create by a family of closely related curves which, when graphed together, suggest a surface.  As we see in the example above, the family of curves suggests a spiraling ribbon in which several brightly colored balls are nestled.  Dan showed several more examples of this and discussed the process he used to create them.  To see more examples, you can visit his website www.dansmath.com or email him at art@dansmath.com.

Once the talks were over, we had some time for puzzles!  Earlier in the week, when I knew we were not going to have an overabundance of talks, I asked participants to bring some of their favorite puzzles so we could all have some fun after the talks.  We were all intrigued with the wide variety of puzzles participants brought.

My dissection puzzle was actually quite popular — that is, until a few of the participants solved it!

You might recognize this from my recent blog post on geometrical dissections.  The pieces above are arranged to make a square, but they may also be rearranged to make an irregular dodecagon.  Some asked if I had any more copies of this puzzle, but unfortunately, I didn’t.  Maybe I’ll have to start making some….

As has been our tradition, many of us went out to dinner afterwards.  We went to our favorite nearby Indian buffet, and engaged in animated conversation.  Interestingly, after talking a bit about mathematics and art, Chamberlain began entertaining us with his wide repertoire of word puzzles.

To give just one example, he asked us to come up with what he calls “mismisnomers.”  Usually, the prefix “mis-” means to incorrectly take an action, as in “misspell.”  But some words, like “misnomer,” begin with “mis-,” while the remainder of the word, “nomer” is not even a word!  How many mismisnomers can you think of?  This and similar amusing puzzles kept us going for quite a while, until it was finally time to head home for the evening.

So that’s all for the Bay Area Mathematical Artists in 2017.  Stay tuned in 2018…our first meeting next year will be at the end of January, and I’ll be sure to let you know how it goes!

## Mathematics and Digital Art: Final Update (Fall 2017)

Yes, it is the end of another semester of Mathematics and Digital Art!  It was a very different semester than the first two, as I have mentioned in previous posts, since I began the semester with Processing right away.  There are still a few wrinkles to iron out — for example, we had a lab project on interactivity (involving using key presses to change features of the movie as it is running) which was quite a bit more challenging than I expected it would be.  But on the whole, I think it was an improvement.

So in this final post for Fall 2017, I’d like to share some examples of student work.  In particular, I’ll look at some examples from the Fractal Movie Project, as well as examples of Final Projects.

Recall that the Fractal Movie Project involves using linear interpolation on the parameters in affine transformations in order to make an animated series of fractal images.  One student experimented with a bright color palette against a black background.  As the fractal morphed, it actually looked like the red part of the image rotated in three dimensions, even though the affine transformations were only two-dimensional.

Cissy wanted to explore the motion of rain in her movie.  Although she began with bright colors on a black background, once she saw her fractal in motion, she decided that more subtle colors on a white background would be better suited to suggest falling raindrops being blown about by the wind.

Sepid also incorporated movement in her movie — she created a rotating galaxy with a color palette inspired by the colors of the Aurora Borealis.  In addition, she learned how to use the Minim library so she could incorporate sound into her movie as well.  Here is a screen shot from her movie.

Now let’s take a look at a few Final Projects.  Recall that these projects were very open-ended so that students could go in a direction of their choice.  Some really got into their work, with truly inspirational results.  The presentation that Sepid gave at a recent meeting of the Bay Area Mathematical Artists was actually work she was doing on her Final Project (read about it here).

Terry took on an ambitious project. She based her work on a Bridges paper by Adam Colestock, Let the Numbers Do the Walking: Generating Turtle Dances on the Plane from Integer Sequences (read the paper here).  Terry did have some programming experience coming into the course, and so she decided to code all of Adam’s turtle graphics algorithms from scratch! This was no simple task, but she worked hard and eventually accomplished her goal.

Here is a screen shot from one of her movies; Terry wanted to create an interesting visual effect by overlaying multiple copies of the same turtle path.  Since this particular path was not too dense in the plane, she was able to work with thicker lines.

Tera created a movie which involved rotating triangles and moving dots.  Her movie had a strong sense of motion, and incorporated a vibrant color palette. She remarked that working with color in this project was both fun and quite challenging. In her words, “Playing nicely with hot pink is not an easy feat.”

I would also like to share the fact that Professor Roza Aceska of Ball State University (Muncie, Indiana) will be teaching a course about digital art next semester using Processing which will be incorporating a lot of my course materials.  I am very excited about this!  Many faculty who come to my talks say they are interested in teaching such a course, but getting Department Chairs and Deans to approve such courses is sometimes an uphill battle.

Professor Aceska’s course will be a bit different from mine — her course is in the Honors Program, and as such, does not count as a mathematics credit.  So she will not have most of the mathematics assignments and quizzes that I had in my course.  But she will still be emphasizing the fascinating relationship between mathematics, programming, and art.  I hope to write more about her course sometime during the next semester.

One final remark — I am helping to organize a Mathematical Art Exhibition at the Golden Section Meeting of the Mathematical Association of America on February 24, 2018 at the California State University, East Bay.  So if you’re reading this and are in the Bay Area and would like to submit some mathematical art for inclusion in our exhibit, please let me know!