Sometimes it's not clear which tech needs to be researched to improve your chances of getting the tech you really want to research, and most players don't have access to the tech tree to see what techs lead to desired techs.

For some reason, I do have access to the tech tree, so I unlocked all techs using the console, made screenshots, then cut and pasted the parts into a complete tech tree for each part of the tree.

If you want to look at them, they can be downloaded here.

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UPDATE   August 27

I realized today that some techs are missing from these tech trees, so the link has been removed.  See this post for updated tech trees.