Combinatorics / CONCEPT

An exhausted lower chain

Let p have size n at least four and maximum second. Assume the upper values after its first two entries decrease, no lower value has both a smaller and a larger lower value later, and adjacent values are never consecutive, where upper and lower are relative to its first entry. If the minimum has even zero-based position k at least two and the first entry equals k/2 + 1, then either n = k + 1 and p = E(k/2), or n = k + 2 and p = P(k/2 + 1).