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I have a proper model category and in it two coequalisers, $A_i \rightrightarrows B_i \to C_i$, $i=1,2$. I have a map of diagrams arising from maps $A_1 \to A_2$, $B_1 \to B_2$ where these two arrows are cofibrations. Can I reasonably expect the canonical arrow $C_1 \to C_2$ to be a cofibration? Are there additional properties on the model category I can assume such that it is?

It may help that the maps $A_i \to B_i$ could also be cofibrations, if I am not mistaken.

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No. Think of examples in which $A_1$ is initial (so $B_1=C_1$). There's no reason why $B_1\to C_2$ should be a cofibration just because $B_1\to B_2$ is.

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Thanks Tom. I think there must be something more at work in my example, then... – David Roberts Apr 6 2011 at 2:44

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