### by Austin Lei, Justin Yokota, and Moor Xu

### Answer:

TANGRAM

Upon opening the puzzle, we see sets of diagrams, each with images and circles, linked together by arrows. Different arrows have different icons. The first set of circles show images for all of the circles, each of which can be identified.

We then can use these clues to infer the meaning of the the arrows and their icons:

Icon | Meaning | Example |
---|

| Derivative (not just mathematical definition) | Nut → Nut butter |

| Substring | perm → permit |

| Adding co- to start of word | bra → cobra |

| x 1000 | kilo → mega |

| Element of/type of | March → Months |

| Concatenate | F + B → FB |

| Abbreviate | Facebook → FB |

| NATO letters | N → November |

| Element symbol | Boron → B |

| Animal collective noun | cobra → quiver |

| Inverse (not just mathematical definition) | sqrt(x) ↔ x^{2} |

Upon determining the meaning of the arrow symbols, we can solve the later diagrams. It is also possible to use the later diagrams to determine the meaning of the arrow symbols that may not be as clear to obtain from the first diagram.

Upon solving all 6 subparts, we can solve the extraction diagram to arrive at a circle containing -log(cos(gram)). The derivative of this is tan(gram), giving the final answer **TANGRAM**.

## Authors' Notes

This puzzle was inspired by category theory, hence the title of the puzzle and the co-arrow. In fact, the clue that was the spark for the puzzle was the cluing of coconut → conut → nut → nut butter. However, it ended up being hard to find more dumb math jokes we could include, and for the sake of making the puzzle more accessible, we removed the category theory notion of co- meaning duals.

I still don’t like category theory.

## Appendix: Solved Diagrams