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math.CO2026

Almost Empty Monochromatic Polygons in Planar Point Sets

Bhaswar B. Bhattacharya, Sandip Das, Sk Samim Islam +2

For integers , , and , let denote the smallest integer such that any set of at least points in th…

math.CO2026

Strong Edge Colouring of Disk Graphs: A 6-Approximation and an Improved Unit-Disk Bound

Sandip Das, Sk Samim Islam, Aashirwad Mohapatra +2

A strong edge colouring of a graph is an edge colouring in which every colour class is an induced matching. The minimum number of colours is the strong chromatic index $χ'_s(G)…

math.CO2026

Large Planar Point Sets Contain 4 Collinear Points or Almost 7-Cliques, and Related Results

Bhaswar B. Bhattacharya, Sandip Das, Sk Samim Islam +2

We prove that every sufficiently large finite planar point set contains either four collinear points or seven points with at most one non-visible pair. More generally, we show that…

math.CO2026

An Improved Upper Bound for the Turán Number of the Hexagon

Sandip Das, Sk Samim Islam, Aashirwad Mohapatra +1

For a graph , the Turán number is the maximum number of edges in an -vertex graph containing no copy of . Determining the Turán numbers of even cy…

math.CO2026

Exact-Distance Domination in Grid Graphs

Sandip Das, Sweta Das, Arpan Sadhukhan

Let be the square grid, and let . A set is an \emph{exact-distance -dominating set} if every vertex has a…

math.CO2026

Parameterized complexity of -Hop, -Step, and -Hop Roman Domination

Sandip Das, Sweta Das, Sk Samim Islam

The \textsc{Dominating Set} problem is a classical and extensively studied topic in graph theory and theoretical computer science. In this paper, we examine the algorithmic complex…

math.CO2026

On the Number of Almost Empty Monochromatic Triangles

Bhaswar B. Bhattacharya, Sandip Das, Sk Samim Islam +3

In this paper, we consider the problem of counting almost empty monochromatic triangles in colored planar point sets, that is, triangles whose vertices are all assigned the same co…