The combinatorial non-crossing-sums inequality

Let k1,k2,k3k_1,k_2,k_3 be odd natural numbers. For each i=1,2,3i=1,2,3, let yi,1,,yi,kiy_{i,1},\ldots,y_{i,k_i} be distinct real numbers, and set yi,0=yi,ki+1=y_{i,0}=y_{i,k_i+1}=-\infty. For two finite pairs of real numbers, call their sums non-crossing when the two sums of one choice and the two sums of the other choice do not alternate in order. Assume:

  1. For each 1i31\le i\le3 and 0p<qki0\le p<q\le k_i of the same parity, the pairs {yi,p,yi,p+1}\{y_{i,p},y_{i,p+1}\} and {yi,q,yi,q+1}\{-y_{i,q},-y_{i,q+1}\} have non-crossing sums.
  2. For 0piki0\le p_i\le k_i of the same parity, the three pairs {y1,p1,y1,p1+1}\{y_{1,p_1},y_{1,p_1+1}\}, {y2,p2,y2,p2+1}\{y_{2,p_2},y_{2,p_2+1}\}, and {y3,p3,y3,p3+1}\{y_{3,p_3},y_{3,p_3+1}\} have non-crossing sums.

Combinatorial formulation conjecture. Then

i=13j=1ki(1)j1yi,j<0.\sum_{i=1}^3\sum_{j=1}^{k_i}(-1)^{j-1}y_{i,j}<0.

This is an almost purely combinatorial formulation of the symmetric area inequality. It is stated as an open conjecture in the paper.

Sources & referencesView supporting material

Primary source

Terence Tao, “An integration approach to the Toeplitz square peg problem”, arXiv:1611.07441 (2017).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.