[xenihn]

You forget complex things that you don't use regularly. Math, spoken languages, written languages, coding...of course you can re-learn it, and re-learning is faster than learning it for the first time.

Based on speaking to my managers in the past, it seems like a year-long lapse is enough for you to lose an incredible amount of retained knowledge/skill. But it's not a permanent loss.

[markus_zhang]

Yeah agreed, sometimes reading a research paper from the DS team would actually ring a bell somewhere and I know where to look at. I'm re-learning Statistics from bottom up at the moment lol but this 2,000-page book really looks daunting. I'm pretty sure I didn't take any advanced optimization course back in university.