# Mathematics A to Z: Part 2

Last summer, Nebus Research had a fun series on the definitions of 26 different mathematical terms, one for each letter of the alphabet. Here are the words from F to J:

F is for fallacy, or a mathematical argument can includes incorrect reasoning.

G is for graph, as in graph theory (as opposed to an ordinary $x-y$ Cartesian graph.

H is for hypersphere, which is the generalization of a circle or sphere into $n-$dimensional space. As a student, one of my favorite formulas was the one for the volume of a hypersphere in $\mathbb{R}^n$:

$V_n = \displaystyle \frac{\pi^{n/2}}{\Gamma(1 + n/2)}$

I is for into, a possible characteristic of a function $f : A \to B$.

J is for jump discontinuity, of the concepts that shouldn’t be brand-new to students at the start of a calculus class but often is.