# The Week in Math: July

Here are the highlights from the historical world of mathematics for the month of July. While this list is not meant to be all-encompassing, I have tried to pick out those things that I find most interesting.

**July 1:**

*Birthdays:* Gottfried Leibniz (1646-1716)

*Deaths:* Richard Buckminster Fuller (1895-1983)

**July 4:**

*Math News:* In 1843, Liouville announces that he has found a solution (in the writings of Galois) to the problem as to whether or not a general fifth degree polynomial is solvable by radicals. (See MathDL for details.)

**July 5:**

*Math News:* In 1698, Johann Bernoulli defines the term “function“. The term was first used by Leibniz. (See MathDL for details.)

**July 6:**

*Birthdays:* Johann Muller Regiomontanus (1436-1476)

*Deaths:* Georg Simon Ohm (1789-1854)

**July 8:**

*Deaths: *Christiaan Huygens (1629-1695)

**July 9:**

*Math News:* In 1814, Gauss writes his last entry into his mathematical diary concerning biquadratic residues and lemniscate functions. This entry will eventually lead to the famous Weil conjectures. (See MathDL for details.)

*Birthdays:* George Darwin (1845-1912)

**July 10:**

*Birthdays:* Roger Cotes (1682-1716)

*Deaths:* Emory McClintock (1840-1916)

**July 11:**

*Math News:* In 1686, Leibniz publishes his results on the Fundamental Theorem of Calculus in Acta Eruditorum. (See MathDL for details.)

*Deaths:* Lillian R. Lieber (1886-1986)

**July 12:**

*Math News:* In 1831, Gauss writes protesting against “the use of an infinite quantity as an actual entity; this is never allowed in mathematics.” (See MathDL for details.)

*Birthdays:* Richard Buckminster Fuller (1895-1983)

**July 13:**

*Deaths:* Johann (III) Bernoulli (1744-1807)

**July 17:**

*Deaths:* Johann (II) Bernoulli (1710-1790), Henri Poincare (1854-1912)

**July 18:**

*Math News:* In 1872, Weierstrass provides the quintessential example of a continuous but nowhere differentiable function (known as the Weierstrass function.) (See MathDL for details.)

*Birthdays:* Robert Hooke (1635-1703), Pierre Laurent (1813-1854), Hendrik Lorentz (1853-1928)

**July 20:**

*Math News:* In 1969, Neil Armstrong becomes the first man on the moon. (See MathDL for details.)

*Deaths:* John Playfair (1748-1819), Bernhard Riemann (1826-1866), Andrei Markov (1856-1922)

**July 22:**

*Math News:* In 1694, Johann Bernoulli sends L’Hospital’s rule to L’Hospital in accordance with their contract. *Click here to read my post on the controversy.* (See MathDL for details.)

*Birthdays:* Wilhelm Bessel (1784-1846)

*Deaths:* William Osgood (1864-1943)

**July 23:**

*Math News:* In 1754, Lagrange publishes his first work concerning the nth derivatives of the product of functions. (See MathDL for details.)

**July 24:**

*Deaths:* Erwin Freundlich (1885-1964)

**July 26:**

*Math News:* In 1976, Kenneth Appel and Wolfgang Haken announce their “controversal” solution to the Four Color Problem. (See MathDL for details.)

*Birthdays:* Lillian R. Lieber (1886-1986)

*Deaths:* Henri Lebesgue (1875-1941), Gottlob Frege (1848-1925)

**July 27:**

*Math News:* In 1837, Dirichlet lectures on his first paper in Analytic Number Theory. In the paper, he proves what will be called Dirichlet’s Theorem. (See MathDL for details.)

*Birthdays:* Johann Bernoulli (1667-1748), Lorand Eotvos (1848-1919), Ernst Zermelo (1871-1953)

**July 28:**

*Math News: *In 1619, Kepler writes to Napier thanking him for his invention of Logarithms. In 1899, Cantor writes toDedekind asking “whether the set of all cardinal numbers is itself a set, because, if it is, it would have a cardinal number larger than any other cardinal.” (See MathDL for details.)

**July 29:**

*Math News:* In 1654, Pascal writes to Fermat, wondering as to whether or not Fermat’s solution to the “problem of points” is correct. (See MathDL for details.)

**July 31:**

*Math News:* In 1669, Barrow sends Newton’s manuscript “De analysi” to Collins, thereby introducing Newton to the world. (See MathDL for details.)

*Birthdays:* Gabriel Cramer (1704-1752)

*Deaths:* Nicolaus(II) Bernoulli (1695-1726)

**References:** If you are interested in additional facts or birthdays, please visit the sites that I used to generate these lists:

- http://mathdl.maa.org – general mathematical facts
- http://www-groups.dcs.st-and.ac.uk:80/~history/Day_files/Now.html – birthdays

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