Multicolor $K_r$-Tilings with High Discrepancy

Abstract

We study the minimum degree threshold $δ_{r,q}$ guaranteeing the existence of $K_r$-tilings of high discrepancy in any $q$-edge-coloring. Balogh, Csaba, Pluhár and Treglown handled the 2-color case, proving that $δ_{r,2} = \frac{r}{r+1}$ for all $r \geq 3$. Here we determine $δ_{r,q}$ for all $q$ large enough, namely $q \geq \binom{r}{2}$. For example, we show that for $r \geq 4$, $δ_{r,q} = \frac{r}{r+1}$ for $\binom{r}{2} \leq q \leq \binom{r+1}{2}$ and $δ_{r,q} = \frac{r-1}{r}$ for $q \geq \binom{r+1}{2}+2$. Thus, $δ_{r,q}$ has a phase transition at $q = \binom{r+1}{2}$, where it drops from $\frac{r}{r+1}$ and then stabilizes at the existence threshold $\frac{r-1}{r}$. We also show that $δ_{r,q} \leq \frac{r}{r+1}$ for all $r,q$, supplementing and giving a new proof for the result of Balogh, Csaba, Pluhár and Treglown.

Figures (6)

• Figure 1: Examples of the construction for $r=3$.
• Figure 2: The bowtie $(v, x_1y_1, x_2y_2)$ and vertices $w_x, w_y$
• Figure 3: Bowties corresponding to Items (a)-(c) of Lemma \ref{['lem: Bowtie']}
• Figure 4: Chaining two $3$-cliques (illustration for the proof of Lemma \ref{['lem:chain aux']}).
• Figure 5: Chaining a $4$-clique to an edge (illustration for the proof of Lemma \ref{['lem:chain']}).

Theorems & Definitions (51)

• Definition 1.1: Discrepancy
• Definition 1.2
• Theorem 1.3: Hajnal-Szemerédi HS:70
• Definition 1.4: $\delta_{r,q}$
• Theorem 1.5
• Theorem 1.6
• Theorem 1.7
• Theorem 1.8
• Lemma 2.3
• Lemma 2.4