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Consider $g_1=x^2, g_2=y^2, g_3=xy+yz\in k[x,y,z]$ with a field $k$. We consider the reverse lexicographic order, and put $x>y>z$. I want to find the generators of the syzygies.

Eisenbud CA book, p739, exercise 15.27, says that it is $(y^2,-x^2,0),(0,x+z,-y),((x+z)y,0,-x^2).$

However my computation yields $(y^2,-x^2,0),(0,x+z,-y),(y,0,-x+z).$

Which is the correct generators?

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    Oh, not the upward arrow but the check mark! I did it just right now! Thank you.2012-09-27

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Eisenbud has got it right here. You can check directly that your third proposed generator is not an element of the kernel of the map from the free $k[x,y,z]$-module on basis $g_1,g_2,g_3$ to $(g_1,g_2,g_3)\subseteq k[x,y,z]$: $(y,0,-x+z)$ maps to $x^2y-x^2y-xyz+xyz+yz^2=yz^2$. On the other hand $((x+z)y,0,-x^2)$ maps to $x^3y+x^2yz-x^3y-x^2yz=0$.

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    Thank you. I understood. I should have read CA book more carefully. But now I have learned meuch better. Thanks2012-09-28