Let $X$ be a set, $(R, +, \cdot)$ be a ring and let $f:X\mapsto R$ be a function. A zero of a function $f$ is a point $\alpha\in X$ such that $f(\alpha)=0$, where $0\in R$ denotes the zero element of the ring $R$. A zero of a function is sometimes called a root of the function.
Chapters: 1 2
Corollaries: 3
Definitions: 4
Proofs: 5 6 7
Propositions: 8 9 10
Theorems: 11 12
