If is a left skew derivation on , then we can construct the (left) skew polynomial ring , which is made up of polynomials in an indeterminate and left-hand coefficients from , with multiplication satisfying the relation
![$ R[\theta;\sigma,\delta]$](http://images.planetmath.org:8080/cache/objects/373/l2h/img3.png "$ R[\theta;\sigma,\delta]$"){kind=small}
