4 papers · 1 filter
An Exhaustive Census of Main-Diagonal Symmetric Costas Arrays of Orders 37-42
Bogdan Dumitru, Cristian Budala
We determine by exhaustive enumeration all main-diagonal symmetric Costas arrays of orders 37 through 42. There are 4 arrays of order 37, none of order 38, 16 of order 39, 2 of ord…
Alternating Extremes in Graceful Labelings of Full Binary Trees and Spider Trees
Bogdan Dumitru, Mihai Nacu
We study a pinned form of graceful labeling. For full binary trees, we ask whether some deepest root-to-leaf path can carry the alternating extreme pattern . Suc…
Notes on the 33-point Erdős--Szekeres problem
Bogdan Dumitru
The determination of is the first open case of the planar Erdős--Szekeres problem, where the general conjecture predicts . We present a SAT encoding for the 33-po…
Two-colorings of finite grids: variations on a theorem of Tibor Gallai
Bogdan Dumitru, Mihai Prunescu
A celebrated but non-effective theorem of Tibor Gallai states that for any finite set of and for any finite number of colors there is a minimal such that no colo…