Template:Selected anniversaries/May 15: Difference between revisions
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File:Johannes Kepler 1610.jpg|link=Johannes Kepler (nonfiction)|1618: [[Johannes Kepler (nonfiction)|Johannes Kepler]] confirms his previously rejected discovery of the third law of planetary motion (he first discovered it on March 8 but soon rejected the idea after some initial calculations were made). | File:Johannes Kepler 1610.jpg|link=Johannes Kepler (nonfiction)|1618: [[Johannes Kepler (nonfiction)|Johannes Kepler]] confirms his previously rejected discovery of the third law of planetary motion (he first discovered it on March 8 but soon rejected the idea after some initial calculations were made). | ||
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||1993: Herbert Grötzsch dies ... mathematician. He was born in Döbeln and died in Halle. Grötzsch worked in graph theory. He was the discoverer and eponym of the Grötzsch graph, a triangle-free graph that requires four colors in any graph coloring, and Grötzsch's theorem, the result that every triangle-free planar graph requires at most three colors. Pic. | ||1993: Herbert Grötzsch dies ... mathematician. He was born in Döbeln and died in Halle. Grötzsch worked in graph theory. He was the discoverer and eponym of the Grötzsch graph, a triangle-free graph that requires four colors in any graph coloring, and Grötzsch's theorem, the result that every triangle-free planar graph requires at most three colors. Pic. | ||
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Revision as of 22:47, 26 January 2022
1618: Johannes Kepler confirms his previously rejected discovery of the third law of planetary motion (he first discovered it on March 8 but soon rejected the idea after some initial calculations were made).
1801: Mathematician Joseph Ludwig Raabe born. He will discover Raabe's ratio test, which determines the convergence or divergence of an infinite series, in some cases.
1836: Astronomer Francis Baily observes "Baily's beads" during an annular eclipse.
1973: Cryptologist Laurance Safford born. Safford established the Naval cryptologic organization after World War I, and headed the effort more or less constantly until shortly after the Japanese attack on Pearl Harbor.