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Boundedness at the Riemann-constants shift for the finite-gap Boussinesq solution

Prove that, when the constant vector C in the finite-gap solution is chosen to be the vector of Riemann constants u[K], the finite-gap Boussinesq solution w(x,t) = −3 ℘_{1,1}(u + C) and v(x,t) = 2 ℘_{1,1,1}(u + C) − (3/2) ℘_{1,2}(u + C) (with u = (x, t, 0, …)^t) is bounded for all x,t.

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Background

The explicit finite-gap solution obtained in the paper expresses the Boussinesq fields in terms of Kleinian ℘-functions associated with the (3,3N+1)-curve. Numerical exploration shows solutions with singularities for various shifts C in the Jacobian.

The authors conjecture that taking C equal to the vector of Riemann constants u[K] yields bounded solutions. Establishing boundedness at this canonical shift would provide a constructive route to non-singular finite-gap solutions and clarify the role of the half-period structure in controlling poles of ℘-functions.

References

Conjecture. Let $\bm{C} = u[K], then the finite-gap solution KdVSolRealCond is bounded.

KdVSolRealCond:

w(x,t)=31,1(u+C),u=(x,t,0,)t,v(x,t)=21,1,1(u+C)321,2(u+C).\begin{split} &w(x,t) = - 3 \wp_{1,1} ( u + \bm{C}),\qquad u = (x, t, 0, \dots)^t,\\ &v(x,t) = 2 \wp_{1,1,1}(u+ \bm{C}) - \tfrac{3}{2} \wp_{1,2}(u+ \bm{C}). \end{split}

Algebro-geometric integration of the Boussinesq hierarchy (2507.19179 - Bernatska et al., 25 Jul 2025) in Conjecture 3, Section "Reality conditions"