The PolynomialReduce returns a list representing a reduction of a specified polynomial in terms of a specified list of polynomials.

$\mathrm{with}\left(\mathrm{MmaTranslator}\left[\mathrm{Mma}\right]\right)\:$

$\mathrm{PolynomialReduce}\left(a{x}^5-5x^3+x^2+a\,\left\{a\,x\right\}\right)$

$\left[\left[x^5+1\,-5x^2+x\right]\,0\right]$

$\mathrm{with}\left(\mathrm{MmaTranslator}\right)\:$

$\mathrm{FromMma}\left(\mathrm{`PolynomialReduce[a\; x^5\; -\; 5\; x^3\; +\; x^2\; +\; a,\; \{x,\; a\}]`}\,\mathrm{evaluate}\right)$

$\left[\left[x^{4}a-5x^2+x\,1\right]\,0\right]$