# Who is Bernhard Bolzano?

December 14, 2020Bernhard Bolzano was born on October 5, 1781 in Prague, died on December 18, 1848 in Prague. He was a Czech philosopher and mathematician of Italian descent.

His father was an Italian immigrant and a small shopkeeper. Her mother was also the daughter of a family in Prague that dealt with hardware. Bolzano studied philosophy, physics, mathematics and theology at the University of Prague. In 1807 he was appointed professor of religion and philosophy at the same university in Prague. Until 1816 he gave successful lectures at this university. In 1816, he was blamed for his beliefs because it contradicted the belief, feeling, and thought adopted by the Christian church. In 1820, the Austrian government expelled Bolzano because of these devastating and hurtful speeches to them.

Bolzano was a Czech philosopher of Italian descent. He was also a good logician and a very good mathematician. Bolzano was more accused of rationality in 1820. He had a philosophy and thought based on mathematics. Hence he opposed Kant’s idealism. He was actually a Catholic priest. After 1805 he taught philosophy of religion at Prague University. He worked on the calculus of infinity and infinitesimals in mathematics. His book “Paradoxes on Infinity” was published in 1851. He has also worked on point clusters.

Bolzano’s most tragic years occurred between 1819 and 1825. He is punished by the University of Prague for not teaching or broadcasting for 7 years. This university professorship is also taken away. Against all these pressures, his high mind has always worked. He has published numerous publications in analysis, geometry, logic, philosophy, and religion. He used the famous Bolzano-Weierstrass theorem as we know it today in analysis for the first time in his book “Functions”. However, he gives the proof of the theorem in his previous work and this work as a source. However, this study and source mentioned has not been found so far. It is highly probable that the proof of a theorem that is widely used and which he has used a lot was given by Bolzano. If the proof of this theorem had not been given, it would not have been used so much by Bolzano. The proof of this theorem was given by Weierstrass in the following years. Therefore, this theorem is known in analysis as the Bolzano-Weierstrass theorem.

Bolzano’s fundamental work is on the paradox of the infinitesimal. Unfortunately, Bolzano was not able to publish these works during his lifetime, as the publication was banned. His “Paradoxes of the Infinites” was only published in 1850, two years after his death. This work includes many properties of infinite series. Like many other mathematicians, Bolzano died in Prague on 18 December 1848.