Definition:Gaussian Binomial Coefficient

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Definition

Let $q \in \R_{\ne 1}$, $r \in \R$, $m \in \Z_{\ge 0}$.

The Gaussian binomial coefficient is an extension of the more conventional binomial coefficient as follows:

\(\displaystyle \binom r m_q\) \(:=\) \(\displaystyle \prod_{k \mathop = 0}^{m - 1} \dfrac {1 - q^{r - k} } {1 - q^{k + 1} }\)
\(\displaystyle \) \(=\) \(\displaystyle \dfrac {\paren {1 - q^r} \paren {1 - q^{r - 1} } \cdots \paren {1 - q^{r - m + 1} } } {\paren {1 - q^m} \paren {1 - q^{m - 1} } \cdots \paren {1 - q^1} }\)


Also known as

Some sources refer to this concept as a $q$-nomial coefficient.

Some use $q$-binomial coefficient.

However, $\mathsf{Pr} \infty \mathsf{fWiki}$'s view is that by referring to a construct by the specific names of the variables in which it is stated limits its flexibility of expression.


Also see

  • Results about Gaussian binomial coefficients can be found here.


Source of Name

This entry was named for Carl Friedrich Gauss.


Sources