Noob questions: Plonk Paper

Hi, I really hope this is the right place to post my noob question. Otherwise please let me know where would be better. I am implementing Plonk as a hobby project in Python.

My question is about the linearisation polynomial in the 4th proving round p.28:


The second and last summand I see a plain z. I just wonder if thats a typo? It just feels like that should be the evaluation challenge?

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Hi,
Indeed this is a typo :slight_smile: Thanks for noticing, will be updated on eprint.

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Ah cool! Thanks for the answer! I managed to implement the protocol now. I am really proud now:D.

There was one thing I stumbled over: In round 3 when t is split up, I needed to factor out x^(n+2), not x^n as the paper says. My understanding is that the third summand of t determines the degree as (n+1) + (n+1) + (n+1) + (n+2) - n = 3n+5…

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The splitting of t in the last section indeed seems to ignore the additional factors for zero-knowledge that increase degree a bit

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