# Specific Hints for Puzzle 2.1 (Crossword Puzzle)

Here are hints for some of the definitions in the crossword puzzle.

Definition 1 (click to display)

A term in group theory = Distance traveled in a year by a planet.

Definition 2 (click to display)

A term in vector algebra = long and narrow (as a shape) + type of long sandwich + space

Definition 3 (click to display)

P(x)/Q(x)

Definition 4 (click to display)

A term in ring algebra: I=aR.

Definition 5 (click to display)

$z \in \mathbb{C}$

Definition 6 (click to display)

A labeled structure in a poset.

Definition 7 (click to display)

$sts = tst$, for example.

Definition 8 (click to display)

A dividing wall in a flying machine.

Definition 9 (click to display)

$G \times X \to X, (g,x) \mapsto g \cdot x$

Definition 10 (click to display)

A set of cones whose union is the whole space.

Definition 11 (click to display)

Which language is this?

Definition 12 (click to display)

$\mathbbm{1}_A: A \to \{0,1\}$

Definition 20 (click to display)

A dividing wall that doesn’t traverse.

Definition 22 (click to display)

Definition 25 (click to display

Look up the name of the corresponding geological period.

Definition 26 (click to display)

A certain type of commutative ring.

Definition 29 (click to display)

A term in graph theory = a big vegetal thing that spreads out.

Definition 31 (click to display)

Also known as Gaussian elimination.