Conditional law of large numbers for directed last passage percolation

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Let a,b>0a,b>0 and let 1ρˉ\frac{1}{\bar{\rho}} be the lower and ρˉ\bar{\rho} the upper slope determined by the conditioning parameters, with ρˉ=ρˉnumρˉden\bar{\rho}=\frac{\bar{\rho}_{\rm num}}{\bar{\rho}_{\rm den}} as in the source. For (x,y)R+2(x,y)\frac{}{ }\in\mathbb R_+^2, define

Ω1={(x,y)(1,)2:1ρˉ<y1x1<ρˉ},Ω2={(x,y)R+2:1ρˉ<yx<ρˉ}.\Omega_1=\{(x,y)\in(1,\infty)^2: \frac{1}{\bar{\rho}}<\frac{y-1}{x-1}<\bar{\rho}\},\qquad \Omega_2=\{(x,y)\in\mathbb R_+^2: \frac{1}{\bar{\rho}}<\frac yx<\bar{\rho}\}.

Under the assumptions of the conditional law of large numbers theorem, let hh denote the limiting shape function and condition on L(aN,bN)=N\mathcal L(aN,bN)=\ell N.

Conditional law of large numbers conjecture. The convergence in the conditional law of large numbers holds with

h(x,y)={+Lˉ(a,b)(xa,yb),(x,y)Ω1,12[(+ab)x+(a+b)yxyD],(x,y)Ω2Ω1,Lˉ(xa,yb),(x,y)R+2Ω2.h(x,y)=\begin{cases} \ell+\bar{\mathcal L}_{(a,b)}(xa,yb),&(x,y)\in\Omega_1,\\ \frac12\left[(\ell+a-b)x+(\ell-a+b)y-|x-y|\sqrt D\right],&(x,y)\in\Omega_2\setminus\Omega_1,\\ \bar{\mathcal L}(xa,yb),&(x,y)\in\mathbb R_+^2\setminus\Omega_2. \end{cases}

This conjecture describes the macroscopic conditional profile throughout the positive quadrant: inside the high-time region the profile contains the conditioned value, in the intermediate region it is linear, and outside it has the usual limiting shape. Its status is unresolved in the supplied source.

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Primary source

Jinho Baik, Dylan Cordaro and Tejaswi Tripathi, “Conditional exponential directed last passage percolation under a one-point upper large deviation event”, arXiv:2508.04954 (2026).

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