I remember reading an article years ago (mid-2000s, must have been) about an entire book that used palindromes extensively. I believe it was sci-fi-adjacent, on

I remember reading an article years ago (mid-2000s, must have been) about an entire book that used palindromes extensively. I believe it was sci-fi-adjacent, only thing I remember distinctly was something called "ylyly" in the book. Ylyly was a planet, I think. Haven't ever been able to find this again. Anyone know what I'm talking about?