Solution (source code)

= Solution

\b[The claimed sufficient condition is false for the printed all-colours requirement.] This is a <polychromatic hypergraph colouring> problem, which is stronger than merely avoiding monochromatic edges.

For a counterexample even with $k=3$, take $V=\{1,2,3,4\}$ and all four triples as edges. Every edge meets the other three, so $m=3$, and
$$
e(2m+2)=8e<27=3^k.
$$
Any assignment of three colours to four vertices repeats a colour on a pair. Any triple containing that pair has at most two colours. Thus this <uniform hypergraph> satisfies the numerical hypothesis but has no required colouring. A single two-vertex edge would already provide a smaller counterexample if $k=2$ is allowed.

Here is the <correlation graph of events> argument that correctly applies to the printed colouring definition. Colour each vertex independently and uniformly with three colours, and let $B_E$ be the event that edge $E$ misses some colour. For $k\geq1$, the <inclusion-exclusion principle> gives
$$
q:=\mathbb P(B_E)=3(2/3)^k-3(1/3)^k.
$$
Join two bad events when their edges intersect. This is a <dependency graph of events>, hence also a <correlation graph of events>, of maximum degree at most $m$: each $B_E$ depends only on colours on $E$, which are jointly independent of the colours on all disjoint edges. Precisely, the symmetric <Lovász local lemma> says that events of probability at most $q$ with such a graph have positive simultaneous avoidance <probability> whenever $eq(m+1)\leq1$. It follows from the asymmetric form $q\leq x(1-x)^m$, taking $x=1/(m+1)$ for $m\geq1$ and using $(m/(m+1))^m\geq e^{-1}$; the case $m=0$ is direct independence.

Thus a valid replacement sufficient condition is
$$
\boxed{e(m+1)\left[3(2/3)^k-3(1/3)^k\right]\leq1,}
$$
or the simpler, stronger condition $3e(m+1)\leq(3/2)^k$. Under either replacement, avoiding all $B_E$ gives exactly the requested <polychromatic hypergraph colouring>. For infinitely many vertices, finite subfamilies can be coloured and compactness of the product of three-point spaces extends this to all constraints; positive simultaneous avoidance probability is only asserted for finite families. The printed $3^k$ bound cannot be justified by substituting monochromatic-event probabilities for missing-colour probabilities.