Function verify_sumcheck_outputs

pub fn verify_sumcheck_outputs<F>(
    claims: &[SumcheckClaim<F, IndexComposition<BivariateProduct, 2>>],
    univariate_challenge: F,
    unskipped_sumcheck_challenges: &[F],
    sumcheck_output: BatchSumcheckOutput<F>,
) -> Result<BatchSumcheckOutput<F>, Error>
where
    F: TowerField,

Verify the validity of sumcheck outputs for the reduction zerocheck.

This takes in the output of the batched univariatizing reduction sumcheck and returns the output that can be used to create multilinear evaluation claims. This simply strips off the evaluation of the multilinear extension of Lagrange polynomials evaluations at univariate_challenge (denoted by $\hat{u}_1$) and verifies that this value is correct. The argument unskipped_sumcheck_challenges holds the challenges of the sumcheck following the univariate round.