On the history of graph theory. Origin
The family tree as an ancient unscientific use of graphs is not always a tree in the mathematical sense and may include cycles. Another ancient unscientific use of graphs is the image of the starry sky: - just a drawing of stars - a graph without edges; - asterisms and arrangements of stars of constellations can be both “minimal“ trees and graphs with cycles; - figures and regions of constellations in the starry sky are hypergraphs. The authors proposed the year 1542 as the year of the probable appearance of the Konigsberg bridges problem. The authors believe that the first report on graph theory was made by Leonhard Euler in 1735 at a Conference of the St. Petersburg Academy of Sciences and is devoted to the Konigsberg bridges problem. The authors believe that the first letter on graph theory by Karl Leonhard Gottlieb Ehler was sent to Leonhard Euler on March 9 (20), 1736 with the question of “the construction of the seven Konigsberg bridges“.