Giusto Bellavitis

{{Short description|Italian mathematician, senator and municipal councilor (1803–1880)}}

{{Infobox scientist

| name = Giusto Bellavitis

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| image = Giusto Bellavitis.jpg

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| birth_date = {{birth date |1803|11|22|df=y}}

| birth_place = Bassano, Vicenza

| death_date = {{death date and age |1880|11|06 |1803|11|22|df=y}}

| death_place = Tezze sul Brenta (near Bassano)

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| nationality = Italian

| fields = Geometry

| workplaces = University of Padua

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| alma_mater = University of Padua

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| known_for = Equipollence

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| spouse = Maria Tavelli

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Giusto Bellavitis (22 November 1803 – 6 November 1880) was an Italian mathematician, senator, and municipal councilor.Charles Laisant (1880) "Giusto Bellavitis. Nécrologie", Bulletin des sciences mathématiques et astronomiques, 2nd série, 4(1): 343–8{{Citation

| last = Carruccio

| first = Ettore

| contribution = Bellavitis, Giusto

| year = 1970

| title = Dictionary of Scientific Biography

| editor-last = Gillispie

| editor-first = Charles Coulston

| volume = 1

| pages = 590–592

| place = New York

| publisher = Charles Scribner's Sons

}}

According to Charles Laisant,

:His principle achievement, which marks his place, in the future and the present, among the names of geometers that will endure, is the invention of the method of equipollences, a new method of analytic geometry that is both philosophical and fruitful.

Born in Bassano del Grappa in 1803 to Ernesto Bellavitis and Giovanna Navarini, Giusto studied largely alone. In 1840, he entered Institut Venitian and in 1842 began instructing at Lycee de Vicence. He became professor of descriptive geometry at University of Padua in 1845. With the unification of Italy he took the opportunity to revise the curriculum to include complementary algebra and analytic geometry. Bellavitis married in 1842 and had one son who also taught geometry at the University of Padua.

Bellavitis anticipated the idea of a Euclidean vector with his notion of equipollence. Two line segments AB and CD are equipollent if they are parallel and have the same length and direction. The relation is denoted $AB\; \backslash bumpeq\; CD\; .$ In modern terminology, this relation between line segments is an example of an equivalence relation. The concept of vector addition was written by Bellavitis as:$AB\; +\; BC\; \backslash bumpeq\; AC\; .$ According to Laissant, Bellavitis published works in "arithmetic, algebra, geometry, infinitesimal calculus, probability, mechanics, physics, astronomy, chemistry, mineralogy, geodesy, geography, telegraphy, social science, philosophy, and literature."