Reverend Charles Lutwidge Dodgson, better known by his pseudonym Lewis Carroll as the creator of Alice in Wonderland, proposed in 1866 a new method for computing matrix determinants called Condensation of Determinants.

An elementary proof of Dodgson’s Condensation Method is available from Main, Donor, and Harwood.

Dodgson was a real genious, although with some dark sides Wikipedia.

Anyway, hidden in his poems are some gems of linear algebra. The following lines written by Lewis Carroll read the same horizontally and vertically when cases and nonletter characters are ignored.

I often wondered when I cursed,
Often feared where I would be—
Wondered where she’d yield her love
When I yield, so will she,
I would her will be pitied!
Cursed be love! She pitied me…

See figure. That is an example of a symmetric matrix.

For Math Teachers

Here is a nice homework: Assign integer values to unique words of the poem and compute its determinant with Dodgson’s Method.

Challenge 1: Starting at the top-left corner, read matrix diagonal elements. Explain the meaning of the diagonal message in the Carroll and then in the Dodgson’s sense.

Challenge 2: There are also other hidden messages in that matrix to read. Hint: Move through rows/cols adopting a traveling pattern. Can you find them?