Algebras and their Associated Monomial Algebras

Abstract

Let $R=\oplus_{\Gamma\in\Gamma}R_{\gamma}$ be a $\Gamma$-graded $K$-algebra over a field $K$, where $\Gamma$ is a totally ordered semigroup, and let $I$ be an ideal of $R$. Considering the $\Gamma$-grading filtration $FR$ of $R$ and the $\Gamma$-filtration $FA$ induced by $FR$ for the quotient $K$-algebra $A=R/I$, we show that there is a $\Gamma$-graded $K$-algebra isomorphism $G(A)\cong \bar{A}=R/<\hbox{\bf HT} (I)>$, where $G(A)$ is the associated $\Gamma$-graded $K$-algebra of $A$ defined by $FA$, and $<\hbox{\bf HT}(I)>$ is the $\Gamma$-graded ideal of $R$ generated by the set of head terms of $I$. In the case that $\Gamma$ is an ordered monoid with a well-ordering, this result enables us to lift many nice structural properties of $\bar{A}$ to $A$ theoretically, and the natural connection with Gr\"obner basis theory leads to effective realization lifting information from the associated monomial algebras in both commutative and noncommutative cases.