# Bondal counter example to the Jordan-Holder property in derived categories

Can anybody give me the reference where this counter-example is explained in detail?. Consists on the following Bondal considered a quiver $Q$ with some relations and proved that $D(Q)$ has two different semi-orthogonal decompositions, of length 3 and 2. Also, I don't know anything about quivers, do you think that there is a way to understand this result without a lot of background? Thanks!

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The reason for nonextendability is the fact that the Euler form $\chi(-,-)$ on the orthogonal subcategory $P^\perp$ is skew-symmetric, and so $P^\perp$ does not have exceptional objects. –  Sasha May 17 '13 at 19:28