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Revision difference : zero polynomial
Version 6 Version 5
The {\em zero polynomial} in a ring $R[X]$ of polynomials over a ring $R$ is the additive identity element $\textbf{0}$ of this polynomial ring: The {\em zero polynomial} in a ring $R[X]$ of polynomials over a ring $R$ is the additive identity element $\textbf{0}$ of this polynomial ring:
$$f+\textbf{0} = \textbf{0}+f = f \quad\forall\, f\in R[X]$$ $$f+\textbf{0} = \textbf{0}+f = f \quad\forall\, f\in R[X]$$
All coefficients of the zero polynomial are equal to 0, i.e. All coefficients of the zero polynomial are equal to 0, i.e.
$$\textbf{0} := (0,\,0,\,0,\,...).$$ $$\textbf{0} := (0,\,0,\,0,\,...).$$
Because always Because always
$$f\cdot\textbf{0} = \textbf{0}$$ $$f\cdot\textbf{0} = \textbf{0}$$
and because in general \,$\deg(fg) = \deg(f)+\deg(g)$\, when $R$ has no zero divisors, one may define that and because in general \,$\deg(fg) = \deg(f)+\deg(g)$\, when $R$ has no zero divisors, one may define that
$$\deg(\textbf{0}) = -\infty$$ $$\deg(\textbf{0}) = -\infty$$
or that the zero polynomial has no \PMlinkname{degree}{Monomial} at all. or that the zero polynomial has no \PMlinkname{degree}{Monomial} at all.