# Computing with Thread: Part I

We explored what kind of geometric constructions we can do with thread, chalk and the help of several people...

### We found out...

• how to draw a line
• how to draw a circle ( d = const.)
• how to draw an ellipse ( a + b = const.)
• how to draw multifocal ellipses (a + b + c = const.)
• how to draw egg-shaped curves (3 * a + b = const.)
• how to measure the circumference of a circle

We explored how our thread-based drawing tools could be used to identify points on the surface of shapes in 3 dimensions.

• We discovered the 3d ellipsoid (a + b = const.)
• We found that multifocal 3d ellipsoids have a doughnut-topology.
• We found two different ways to create ellipsoid shapes:
• the polygon method, where the thread forms a polygon going through the focal points and the drawing point
• the star method where the thread is alternately visiting each focal point and the drawing point

### Observations

• Geometric knowledge from school only got us so far ...
• There is a whole universe of "new" shapes and forms

### Questions raised

• Questions regarding surface of different shapes popped up
• We discussed different methods of measuring the surfaces using thread

### Homework

• What could an Experimentier-Baukasten / a kit / a sandbox for computing with thread look like?
Do some research on other kinds of kits!
• Do some thread-based geometry at home. Pick a parameter such as the thread-length and vary it systematically

### Geometry

Some links to classics of compass + straightedge geometry
as well as the thread-based geometry we explored in our class.

### Kitspiration

Here are some links to all kinds of kits.
May they serve as inspiration for creating your own textile computing kits.

## Knots and Splices

### Knot History

• various knot books online and offline
• We learned how ropes are made in a "Seilerei" on the "Reeperbahn"
• We learned about a rope inspection machine, that travels along a the cable of a "Seilbahn"

### Knot Theory

• We learned the basics of knot theory
• Minimum number of crossings
• Knot-Invariants and Knot-Polynomials

### Knot Classification Game

We played a knot identification game.
It goes like this:

• Student A creates two knots using thread.
• Student B tries to figure out whether or not the two knots are the same

### Homework

Create a nice framework for displaying knots.
The framework can be physical, graphical or computational in nature

## Braids

In this class we will identify the basic elements of braids, and explore the intersection of braiding and sorting algorithms...