As someone who has worked for one such secretive hedge fund in the past, and has for a long time been very interested in Renaissance, I'd be curious to know what your source of this information is. Any chance you could share some more insight?
1. I'm friends with multiple people who used to work at Renaissance, and I've directly spoken with folks who are currently there (among other, similar firms).
2. I've read the research published by professors and post-docs before they were hired.
3. I have first hand experience developing forecasts for various market research firms and many hedge funds. I've seen first hand what the difference is between the firms that say they're quantitative and the ones that are quantitative.
Not to discourage you (and you probably already know this) but: since you've already worked in the industry, Renaissance is very unlikely to take you seriously as a candidate. I'm not sure if that's what you meant when you said you're interested, but I figured I'd put it out there.
In any case, contrary to popular belief it's possible to connect the dots on what firms like RenTec do. But just having a high level idea of how they work isn't nearly enough to replicate their success. Their success relies on a large number of interdisciplinary scientists cooperating with the support of an incredibly specialized infrastructure. Getting the cliff notes on how they achieve e.g. dimensionality reduction doesn't come close to cutting it.
Do you have any other keywords? “Learning from few examples” comes to mind...