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Let $G$ be a $k$-connected graph on $n$ vertices. Hippchens Conjecture states that two longest paths in $G$ share at least $k$ vertices. Gutierrez recently proved the conjecture when $kleq 4$ or $kgeq frac{n-2}{3}$. We improve upon both results; namely, we show that two longest paths in $G$ share at least $k$ vertices when $k=5$ or $kgeq frac{n+2}{5}$. This completely resolves two conjectures of Gutierrez in the affirmative.
Let $P,Q$ be longest paths in a simple graph. We analyze the possible connections between the components of $Pcup Qsetminus (V(P)cap V(Q))$ and introduce the notion of a bi-traceable graph. We use the results for all the possible configurations of th
Let $G=(V,E)$ be a multigraph. The {em cover index} $xi(G)$ of $G$ is the greatest integer $k$ for which there is a coloring of $E$ with $k$ colors such that each vertex of $G$ is incident with at least one edge of each color. Let $delta(G)$ be the m
Karasev conjectured that for any set of $3k$ lines in general position in the plane, which is partitioned into $3$ color classes of equal size $k$, the set can be partitioned into $k$ colorful 3-subsets such that all the triangles formed by the subse
In 1972, Erd{o}s - Faber - Lov{a}sz (EFL) conjectured that, if $textbf{H}$ is a linear hypergraph consisting of $n$ edges of cardinality $n$, then it is possible to color the vertices with $n$ colors so that no two vertices with the same color are in
Hadwigers conjecture is one of the most important and long-standing conjectures in graph theory. Reed and Seymour showed in 2004 that Hadwigers conjecture is true for line graphs. We investigate this conjecture on the closely related class of total g