book: Clarify why fixed columns are shown separately in commitments

This commit is contained in:
Jack Grigg 2021-02-12 15:26:28 +00:00
parent 67b6d197aa
commit 126abd151c

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@ -8,8 +8,10 @@ auxiliary, and fixed columns. We define $F_{i,j}$ as the assignment in the $j$th
the $i$th fixed column. Without loss of generality, we'll similarly define $A_{i,j}$ to
represent the advice and auxiliary assignments.
> The only difference between advice and auxiliary columns, is that the commitments to
> auxiliary columns are not placed in the proof, and are instead computed by the verifier.
> We separate fixed columns here because they are provided by the verifier, whereas the
> advice and auxiliary columns are provided by the prover. In practice, the commitments to
> auxiliary and fixed columns are computed by both the prover and verifier, and only the
> advice commitments are stored in the proof.
To commit to these assignments, we construct Lagrange polynomials of degree $n - 1$ for
each column, over an evaluation domain of size $n$ (where $\omega$ is the $n$th primitive
@ -23,9 +25,8 @@ We then create a blinding commitment to the polynomial for each column:
$$\mathbf{A} = [\text{Commit}(a_0(X)), \dots, \text{Commit}(a_i(X))]$$
$$\mathbf{F} = [\text{Commit}(f_0(X)), \dots, \text{Commit}(f_i(X))]$$
$\mathbf{F}$ is constructed as part of key generation (pre-computed by both the prover and
verifier, using a blinding factor of $1$). $\mathbf{A}$ is constructed by the prover and
sent to the verifier.
$\mathbf{F}$ is constructed as part of key generation, using a blinding factor of $1$.
$\mathbf{A}$ is constructed by the prover and sent to the verifier.
## Committing to the lookup permutations