Category Archives: OpenCourseware

Gödel, Escher, Bach: Session 7

A day late. Sorry folks. But I think I may be talking to myself by now. So, since we are at #7, I think I’ll let that be the perfect ending of our little discussion group (for now). I know this was a little ambitious to take on (schedule-wise), so I will re-think another book or topic to do next time.

Current Assignment: For Thursday, October 1
Read: Canon by Intervallic Augmentation and Chapter VI: The Location of Meaning
Listen: Bach never multiplied the intervals of a theme by 3 1/3. He did multiply them by -1 in this canon by exact inversion, the Canon Perpetuus from the Musical Offering. An effect of the exact inversion is that the piece has to oscillate constantly between major and minor chords, and technically it can’t end.

The Dialogue: Canon by Intervallic Augmentation

This Dialogue between Achilles and the Tortoise tries to resolve the question, ‘Which contains more information–a record, or the phonograph which plays it?”

(By the way, how many haikus can you find in this dialogue?)

Rosetta Stone

Chapter VI: The Location of Meaning

This chapter discusses how meaning is divided among coded message, decoder, and receiver. Hofstadter gives examples of strands of DNA, ancient tablets containing undeciphered inscriptions, and some unusual phonographs.
Continue reading →

What’s up with all these GEB posts? If you missed what we’re doing, read here. Remember, I’m no expert on all this, I’m just helping facilitate. I’m trying to read along with the rest of you!

Current Assignment: For Monday, September 28
Read: Little Harmonic Labyrinth and Chapter V: Recursive Structures and Processes
Listen: The Little Harmonic Labyrinth by Johann David Heinichen. Waltz #2 by Billy Joel.

I think the Fall semester has hit most of us and our schedules are slipping away from our control (did we ever really have control??). But, in case someone is still interested in this, I’ll continue to post for a bit more.

red pill or blue pill?

When Justin Curry (MIT) taught this course, he quoted the following at this point in the book:
This is your last chance. After this, there is no turning back. You take the blue pill -the story ends, you wake up in your bed and believe whatever you want to believe. You take the red pill -you stay in Wonderland and I show you how deep the rabbit-hole goes. – Morpheus
Continue reading →

I’ve been a bit under the weather the past few days, but I don’t want to get behind on this project. So… onward!

Current Assignment: Thursday, September 24 (where is the month of September disappearing to!!??)
Read: Contracrostipunctus and Chapter IV: Consistency, Completeness, and Geometry
Listen: Contrapunctus 19 from the Art of Fugue (BWV 1050). This performance abruptly ends in the same place that the score ended due to Bach’s death. Bach left his name in the music, as the German notes B-A-C-H, a few measures before the end.

Summary of Contrastipunctus
This dialogue is central to the book because it contains a set of paraphrases of Gödel’s self-referential construction and of his Incompleteness Theorem. One of the paraphrases of the Theorem says, “For each record player there is a record which cannot play.” The Dialogue’s title is a cross between the word “acrostic” and the word “contrapunctus,” a Latin word which Bach used to denote the many fugues and canons making up his Art of the Fugue. Some explicit references to the Art of the Fugue are made. The Dialogue itself conceals some acrostic tricks.

Escher Relativity

(Brief) Summary of Chapter IV: Consistency, Completeness, and Geometry
The preceding Dialogue is explicated to the extent it is possible at this stage. This leads back to the question of how and when symbols in a formal system acquire meaning. The history of Euclidean and non-Euclidean geometry is given, as an illustration of the elusive notion of “undefined terms.” This leads to ideas about the consistency of different and possibly “rival” geometries. Through this discussion the notion of undefined terms is clarified, and the relation of undefined terms to perception and thought processes is considered.

Discussion Ideas

  1. (for the Dialogue) GEB pp. 81 – For instance, Lewis Carroll often hid words and names in the first letters (or characters) of the successive lines in poems he wrote. Poems which conceal messages that way are called “acrostics”. Might this quote apply to this dialogue?
  2. Why does DRH keep apologizing about his use of the term “isomorphism”?
  3. What’s the problem with interpreting mathematical objects? In the case of the modified pq-system? In the case of Euclidean geometry? What’s wrong with our interpretation of a “straight line”?

(that’s enough to get you started)

Escher Relativity in Legos
Click on the photo to view how this image was created.

Up Next: For Monday, September 28
Read: Little Harmonic Labyrinth and Chapter V: Recursive Structures and Processes
Listen: The Little Harmonic Labyrinth turns out not to be by Bach at all! It was written instead by his much lesser-known contemporary, Johann David Heinichen. Disappointingly, it doesn’t even have a fake resolution near the end, as the dialogue implies. Also, it’s boring. A completely unrelated piece, however, does have a clear “pushing and popping” structure to it, and a fake resolution: Waltz #2 by Billy Joel. Yes, that Billy Joel, retired from pop and writing classical music. Allow Achilles and the Tortoise one more anachronism and pretend this is what they’re listening to.

We spent the weekend at Bald Head Island with family… what a great way to say goodbye to summer. In the BHI Conservancy shop we found a tempting book/kit: M. C. Escher Kaleidocycles: An Illustrated Book and 17 Fun-to-Assemble Three-Dimensional Models.

Kaleidocycles,

According to the publisher:

A Kaliedocycle is a three-dimensional ring made from a chain of solid figures enclosed or bonded [sic] by four triangles. These kaleidocycles are adaptations of Escher’s two-dimensional images of fish, angels, flowers, people, etc., transformed into uniform, interlocking, three-dimensional objects whose patters [sic] wrap endlessly. Kaleidocycles contains a 48-page book with over 80 reproductions and diagrams, assembly instructions, and a fascinating discussion of the geometric principles and artistic challenges underlying Escher’s designs and their transformation to three-dimensional models; and seventeen die-cut, scored, three-dimensional models (11 kaleidocycles and 6 geometric solids).

I was so tempted to buy the set, but I resisted. You might enjoy finding some similar projects online for free (let me know if you find any). Anyway, on to the assignment at hand.

Current Assignment: Monday, September 21
Read: Sonata for Unaccompanied Achilles and Chapter III: Figure and Ground
Listen: Sonata No. 1 for solo violin: Adagio (BWV 1001). If an accompanied version of this exists somewhere, I don’t know where to find it.

Continue reading →

I hope the MU puzzle didn’t discourage too many of you from continuing to read this book (see here for explanation of what we are doing and here for a schedule). I’m going to assume it was a busy weekend and people just didn’t get around to posting anything about the last section. That’s ok. Let’s continue on.

Current Assignment: Thursday, September 17
Read: Two-Part Invention and Chapter II: Meaning and Form in Mathematics
Listen: Two-Part Invention in C major (BWV 772)

Summary of Chapter II:
A new formal system (the pq-system) is presented, even simpler than the MIU-system of Chapter I. Apparently meaningless at first, its symbols are suddenly revealed to possess meaning by virtue of the form of the theorems they appear in. This revelation is the first important insight into meaning: its deep connection to isomorphism. Various issues related to meaning are then discussed, such as truth, proof, symbol manipulation, and the elusive concept, “form.”

Discussion Questions:
What is the difference between meaning in a formal system and meaning in a human language?

What is the difference between active and passive meaning?

For those of you silently reading/skimming along, don’t get discouraged about all this mathematics stuff. We’re just laying a foundation for the meatier discussions to come. I’m hoping you will start to see connections to other areas of study and life.

Up Next: For Monday, September 21
Read: Sonata for Unaccompanied Achilles and Chapter III: Figure and Ground
Listen: Sonata No. 1 for solo violin: Adagio (BWV 1001). Anyone know where to find an accompanied version of this?

Well, we’re off and running (pun intended). I hope you are beginning to see that this book is about much more than the intersection of mathematics, art, and music.

Current Assignment: Monday, September 14
Read: Three-Part Invention and Chapter I: The MU-puzzle
Listen: The Three-Part Ricercar, from the Musical Offering (BWV 1079), introduces the King’s theme (which appears in nearly every piece of the Musical Offering) and the fugue style in general.

Discussion Questions:
(Three-Part Invention)

  1. What story is recreated in this dialogue?
  2. In what ways is this dialogue self-referential?
  3. Is there any significance in positioning the Tortoise upwind of Achilles?

Escher's Mobius Strip

(The MU-Puzzle)

  1. What are some more differences between people and machines? Hofstadter talks a lot about observing patterns, but who is doing the observing and from where?
  2. Do you think that being able to jump out of a task and look for patterns is an inherent property of intelligence? What do you think of the following?

    Of course, there are cases where only a rare individual will have the vision to perceive a system which governs many people’ lives, a system which had never before even been recognized as a system; then such people often devote their lives to convincing other people that the system really is there, and that it ought to be exited from! (pp. 37)

    What, or who, does this make you think of?

  3. Hofstadter calls the U-Mode a “Zen way of approaching things.” (pp. 39) What does this mean?
  4. Is the notion of “truth” different for a theorem than an axiom?

What other rabbit trails we can pursue?

Up Next: For Thursday, September 17
Read: Two-Part Invention and Chapter II: Meaning and Form in Mathematics
Listen: Two-Part Invention in C major (BWV 772)

Bach Mobius Strip

Watch this video of the enigmatic Canon 1 à 2 from J. S. Bachs Musical Offering (1747). The manuscript depicts a single musical sequence that is to be played front to back and back to front. A nice tie-in to our reading of Gödel, Escher, Bach. We’ll be reading about and listening to Crab Canon at the beginning of October.

HT: Patrick Wynne

On Thursday of this week we will begin our group discussion of Hofstadter’s book, Gödel, Escher, Bach (see here for more details). I’m posting this a little early since it is the first assignment/discussion. The plan is to post on Thursdays and Mondays so that participants can start commenting (this means you will have to do the reading BEFOREHAND, so check and follow the schedule!). We’re still working out the best day/format for a live group chat. Stay tuned.

Assignment for Thursday, September 10 (Part I: GEB begins)
Read: Introduction
Listen: Brandenburg Concerto No. 5 (BWV 1050)

GEB
You still have time to order the book from Amazon.com (or pick one up at a used book store, mine was 25¢). This is a no guilt discussion group. If you miss a week, try to jump back in. You can also read/listen ahead by looking at the schedule posted here.

Douglas Hofstadter wrote a very helpful preface to the 20th anniversary edition of the book. The actual content of the book remains unchanged. However, if you read the preface, you will get a good idea of what Hofstadter was hoping readers would “get” in his book. He wrote it because so many people over the years have not understood what he was really trying to say. I guess you could say there was a real chasm between reader response and authorial intention! You can read a fair bit of it by creatively using the Amazon “Look Inside” feature. Actually, you can read all of it if you try hard enough (first puzzle of the course to solve).

Feel free to start posting your thoughts and/or questions on the Introduction!

Up next (For September 14):
Read: Three-Part Invention and Chapter I: The MU-puzzle
Listen: The Three-Part Ricercar, from the Musical Offering (BWV 1079), introduces the King’s theme (which appears in nearly every piece of the Musical Offering) and the fugue style in general.

And now, for something completely different: GEB virtual course

I’ve been thinking of finding some folks to “take” one of MIT’s OpenCourseware classes together.

After thinking through various possibilities (face-to-face bookclub, social networks, listserv, etc), here’s my proposal:

  1. Use my blog as the meeting place and record of conversation for the MIT course: SP.258 / ESG.SP258 Gödel, Escher, Bach


    2. The Penrose triangle, also known as the tribar, is an impossible object. It appears to be a solid triangle made of three straight beams of square cross-section which meet at right angles. It is featured prominently in the works of artist M.C. Escher, whose earlier depictions of impossible objects partly inspired it. (Image by MIT OCW.)

  2. Here’s the course description:

    How are math, art, music, and language intertwined? How does intelligent behavior arise from its component parts? Can computers think? Can brains compute? Douglas Hofstadter probes very cleverly at these questions and more in his Pulitzer Prize winning book, “Gödel, Escher, Bach”. In this seminar, we will read and discuss the book in depth, taking the time to solve its puzzles, appreciate the Bach pieces that inspired its dialogues, and discover its hidden tricks along the way.

  3. In the bricks-and-mortar version of the course, they met twice a week for an hour. In our virtual version, we’ll discuss two sections in a week starting after Labor Day. We’ll follow this reading/listening schedule which follows the same order of the original MIT course. I’ll create a post for each of the reading and listening assignments (one on Mondays and the second on Thursdays). You can join in the discussion at any time during that week but make sure you have done the reading/listening first! It will be most productive if we move through the material together as much as possible. I reserve the option to close comments after a week, so that we keep moving forward and focus on the discussion for the most current reading/listening. However, if you get behind, you should feel free to jump back in later in the semester.
  4. There will be an optional chat discussion once a week. We’ll figure out the format (iChat, AIM, Google chat, etc) and the day and time once I know who is interested.

Who’s interested?

UPDATE: There is now a page (see tab in the blue bar above) for the “Gödel, Escher, Bach” Course Schedule. This page has the reading and listening schedule and links to MP3 files for the music referenced. The dates listed are for when the discussion on the reading/listening will commence (so be prepared ahead of time). If you cannot keep up with the full schedule, you are welcome to participate in whatever chapters you are able to prepare for.

Another resource: MIT’s Highlights for High School recorded six lectures from a summer course (2007): Gödel, Escher, Bach: A Mental Space Odyssey. A good overview of the main concepts in the book. You need RealPlayer to view the one-hour lectures.