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YCor
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Are there three non-commutative polynomials in three variables with finite dimensional quotient?

$\DeclareMathOperator\la{\langle}\DeclareMathOperator\ra{\rangle}$Let $K$ be a field an $K\la x,y,z\ra$ the non-commutative polynomial ring in 3 variables.

Question 1: Are there three (less is probably not possible?!) polynomials $f,g,h \in K\la x,y,z\ra$, which are sums of monomials of degree at least two such that the algebra $K\la x,y,z\ra/(f,g,h)$ is finite dimensional?

Is there a systematic way to construct such polynomials?

For two variables we can take for example $f=xy+yx$ and $g=x^3+y^3$, but I do not know (or forgot) such examples for more than 2 variables.

(If possible we should also have (this is equivalent to $(f,g,h)$ being an admissible ideal) that there exists an $n \geq 2$ such that $J^n \subseteq (f,g,h)$ where $J=\la x,y,z\ra$ is the ideal generated by x,y,z.)

Question 2: Let $f_i$ for $i=1,...,n-1$ be polynomials spanning an admissible ideal in the non-commutative polynomial ring in $n-1$ variables $x_i$. Can we find $g$ such that $\la f_i,g\ra$ is an admissible ideal in $K\la x_i,y\ra$?

Mare
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