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YCor
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Intuition behind the Canonical Projective Resolutioncanonical projective resolution of a Quiver Representationquiver representation

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Mike Pierce
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Let $Q$ be a finite acyclic quiver, and $X$ some representation of $Q$. For $i \in Q_0$ define the $kQ$-modules $P_i = kQe_i$, and $X(i) = e_i X$. The representation $X$ has a canonical projective resolution, called the Ringel resolution, given by $$ 0 \longrightarrow \bigoplus_{a \in Q_1} P_{h(a)} \otimes X(t(a)) \xrightarrow{\quad d \quad} \bigoplus_{i \in Q_0} P_i \otimes X(i) \xrightarrow{\quad f \quad} X \longrightarrow 0 $$ where in each direct summand the maps are given by $$ d(p \otimes x) = p \otimes (a \cdot x) - pa \otimes x \qquad\quad f(p \otimes x) = p \cdot x $$

Does anyone have some intuition for this resolution that they could share? Can the modules and the maps in this resolution be nicely interpreted in terms of the paths in $Q$? And can this interpretation be extended to get us projective resolutions for quivers with relations? Or for non-acylic quivers?

For more details on this resolution, see these lecture notes by Harm Derksen.

Let $Q$ be a finite acyclic quiver, and $X$ some representation of $Q$. For $i \in Q_0$ define the $kQ$-modules $P_i = kQe_i$, and $X(i) = e_i X$. The representation $X$ has a canonical projective resolution, called the Ringel resolution, given by $$ 0 \longrightarrow \bigoplus_{a \in Q_1} P_{h(a)} \otimes X(t(a)) \xrightarrow{\quad d \quad} \bigoplus_{i \in Q_0} P_i \otimes X(i) \xrightarrow{\quad f \quad} X \longrightarrow 0 $$ where in each direct summand the maps are given by $$ d(p \otimes x) = p \otimes (a \cdot x) - pa \otimes x \qquad\quad f(p \otimes x) = p \cdot x $$

Does anyone have some intuition for this resolution that they could share? Can the modules and the maps in this resolution be nicely interpreted in terms of the paths in $Q$? And can this interpretation be extended to get us projective resolutions for quivers with relations? Or for non-acylic quivers?

For more details on this resolution, see these lecture notes by Harm Derksen.

Let $Q$ be a finite acyclic quiver, and $X$ some representation of $Q$. For $i \in Q_0$ define the $kQ$-modules $P_i = kQe_i$, and $X(i) = e_i X$. The representation $X$ has a canonical projective resolution, called the Ringel resolution, given by $$ 0 \longrightarrow \bigoplus_{a \in Q_1} P_{h(a)} \otimes X(t(a)) \xrightarrow{\quad d \quad} \bigoplus_{i \in Q_0} P_i \otimes X(i) \xrightarrow{\quad f \quad} X \longrightarrow 0 $$ where in each direct summand the maps are given by $$ d(p \otimes x) = p \otimes (a \cdot x) - pa \otimes x \qquad\quad f(p \otimes x) = p \cdot x $$

Does anyone have some intuition for this resolution that they could share? Can the modules and the maps in this resolution be nicely interpreted in terms of the paths in $Q$? And can this interpretation be extended to get us projective resolutions for quivers with relations? Or for non-acylic quivers?

Removed the bit about editing the question, since users had to problem addressing them.
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Mike Pierce
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Let $Q$ be a finite acyclic quiver, and $X$ some representation of $Q$. For $i \in Q_0$ define the $kQ$-modules $P_i = kQe_i$, and $X(i) = e_i X$. The representation $X$ has a canonical projective resolution, called the Ringel resolution, given by $$ 0 \longrightarrow \bigoplus_{a \in Q_1} P_{h(a)} \otimes X(t(a)) \xrightarrow{\quad d \quad} \bigoplus_{i \in Q_0} P_i \otimes X(i) \xrightarrow{\quad f \quad} X \longrightarrow 0 $$ where in each direct summand the maps are given by $$ d(p \otimes x) = p \otimes (a \cdot x) - pa \otimes x \qquad\quad f(p \otimes x) = p \cdot x $$

Does anyone have some intuition for this resolution that they could share? Can the modules and the maps in this resolution be nicely interpreted in terms of the paths in $Q$? And can this interpretation be extended to get us projective resolutions for quivers with relations? Or for non-acylic quivers?

I realize that my questions are pretty broad. I'm thinking about this now and working through the details of the exactness of the resolution. If I figure out a way to focus my questions, I'll edit the post.

For more details on this resolution, see these lecture notes by Harm Derksen.

Let $Q$ be a finite acyclic quiver, and $X$ some representation of $Q$. For $i \in Q_0$ define the $kQ$-modules $P_i = kQe_i$, and $X(i) = e_i X$. The representation $X$ has a canonical projective resolution, called the Ringel resolution, given by $$ 0 \longrightarrow \bigoplus_{a \in Q_1} P_{h(a)} \otimes X(t(a)) \xrightarrow{\quad d \quad} \bigoplus_{i \in Q_0} P_i \otimes X(i) \xrightarrow{\quad f \quad} X \longrightarrow 0 $$ where in each direct summand the maps are given by $$ d(p \otimes x) = p \otimes (a \cdot x) - pa \otimes x \qquad\quad f(p \otimes x) = p \cdot x $$

Does anyone have some intuition for this resolution that they could share? Can the modules and the maps in this resolution be nicely interpreted in terms of the paths in $Q$? And can this interpretation be extended to get us projective resolutions for quivers with relations? Or for non-acylic quivers?

I realize that my questions are pretty broad. I'm thinking about this now and working through the details of the exactness of the resolution. If I figure out a way to focus my questions, I'll edit the post.

For details, see these lecture notes by Harm Derksen.

Let $Q$ be a finite acyclic quiver, and $X$ some representation of $Q$. For $i \in Q_0$ define the $kQ$-modules $P_i = kQe_i$, and $X(i) = e_i X$. The representation $X$ has a canonical projective resolution, called the Ringel resolution, given by $$ 0 \longrightarrow \bigoplus_{a \in Q_1} P_{h(a)} \otimes X(t(a)) \xrightarrow{\quad d \quad} \bigoplus_{i \in Q_0} P_i \otimes X(i) \xrightarrow{\quad f \quad} X \longrightarrow 0 $$ where in each direct summand the maps are given by $$ d(p \otimes x) = p \otimes (a \cdot x) - pa \otimes x \qquad\quad f(p \otimes x) = p \cdot x $$

Does anyone have some intuition for this resolution that they could share? Can the modules and the maps in this resolution be nicely interpreted in terms of the paths in $Q$? And can this interpretation be extended to get us projective resolutions for quivers with relations? Or for non-acylic quivers?

For more details on this resolution, see these lecture notes by Harm Derksen.

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Mike Pierce
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