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Bijection between modified path-diagram terms and RC-graphs/pipe dreams

Establish a weight-preserving bijection between the modified path-diagram objects arising from computing the coefficients c_{1,w_0(n)}^{v^{-1}w_0(n)}(x;y) by multiplying factorial elementary symmetric polynomials in increasing order of degree (and sorting columns of the resulting diagram) and the RC-graphs/pipe dreams that index terms in the pipe dream formula for the double Schubert polynomial sch_v(x;y), proving that the sets of terms and their weights coincide.

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Background

RC-graphs (pipe dreams) give a well-known positive combinatorial formula for double Schubert polynomials. The paper introduces diagrammatic objects arising from a path-based multiplication formula and observes empirically that, after a specific modification (computing c_{1,w_0(n)}{v{-1}w_0(n)}(x;y) by multiplying in increasing degree and sorting columns), the resulting terms appear to match those from RC-graphs.

The authors present explicit examples supporting a term-by-term correspondence and weight agreement but do not provide a proof, formulating this as a conjectural bijection.

References

We suspect from empirical evidence, though have not proved, that a modification of our formula for $\sch_v(x;y)$ to computing $c_{1,w_0(n)}{v{-1}w_0(n)}(x;y)$ but applying Proposition \ref{proposition:minipieri} in increasing order of degree instead of decreasing order yields the same terms as the definition of pipe dream polynomials with the corresponding RC-graph obtained directly by sorting the columns of our diagram.

A Molev-Sagan type formula for double Schubert polynomials (2401.11060 - Samuel, 19 Jan 2024) in Section 3 (Positive formula for double Schubert polynomials), Example: Illustration of the conjectural relation to RC-graphs