This is Dan Boneh's video on PLONK - https://www.youtube.com/watch?v=vxyoPM2m7Yg
I went through the video multiple times & also tried to go through the original PLONK paper - https://eprint.iacr.org/2019/953.pdf
Boneh's explanation of PLONK involves the steps
1) Boneh consider's the trace of the equation as the inputs (public & private) & the gates. Let's say there are 3 gates & 3 inputs, each gate can be considered as
$Left$ $o$ $Right$ = $Output$
So 3 gates become 9 points. Adding to this, the 3 points from the 3 inputs. We get a total of 12 points.
So he interpolates a polynomial $P(X)$ of degree 11 using the 12 points.
PLONK Paper:. I don't see the PLONK paper doing this step at all.
2) Boneh proves that this polynomial is the input correctly by interpolating a polynomial $v(X)$ for the 3 inputs & verifies if $P = v$ at the 3 points.
PLONK Paper: Since the PLONK Paper never creates $P(X)$, it doesn't do this step either.
3) Boneh proves that every gate is evaluated correctly
He creates a selector Polynomial $S(x)$ which represents whether a gate is an addition or a multiplication gate & then checks whether the below is true
$S(y)\cdot [P(y) + P(\omega Y)] + (1-S(y))\cdot P(y)\cdot P(\omega Y) = P(\omega^2 Y)$
PLONK Paper: The PLONK Paper does do this though they expresses this polynomial in a slightly different way
$q_L \cdot f_L + q_R \cdot f_R + q_O \cdot f_O + q_M \cdot f_L \cdot f_R + q_C = 0$
Here $q_L$, $q_R$ & $q_O$ act like the selector polynomials & I believe do the same thing which Boneh does with his $S(x)$ selector polynomial.
So I believe this step would match in both cases.
4) Boneh proves that the wiring has been done correctly using a prescribed permuation check.
PLONK Paper: This is also done in the PLONK Paper, they call it "copy constraints" checking using a permutation done by grand product argument.
So this also matches.
So I am confused as to why the first 2 steps aren't covered in the PLONK Paper. And I am just unable to recognize them in the paper? The PAPER covers 10x as much as Boneh's video - in terms of details, proofs, optimisations etc so I may be not recognising it in the paper - which is what i want to find out.
I am looking to find out if those steps get implicitly performed in some other step in the paper - if so, which steps are those?
Or if the same check/purpose is done in a different way (like for e.g. the selector polynomial looks quite different between the two) - if so, I want to know which step is it in the paper?