As you already know from my post 100 Followers I am organizing an event about the mathematicians born in October. As a small reminder you can find this event on: Google+ , Facebook and also you can use #CelebratewithLThMath on Tumblr , Twitter or Instagram. With it I just to show how many people worked and transformed the mathematics we are learning now. Just to make you a little curious there will be approx 37 mathematicians, so far we have 6 mathematicians covered (another 31 there to go). So I wanted to make an update and also share with you what we have learned so far.

**1. Luigi Guido Grandi **born on 1st October 1671 was an Italian monk, mathematician and engineer. He has done a lot of incredible things for math, one of them is studying the rose curve (sin wave plotted in polar coordinates), a curve which has the shape of a petaled flower. He named the rose curve rhodonea.

Grandi also studied this series He came at the good conclusion that this series is equal to 1/2, though he didn’t have the proper concepts to prove it. More exactly the series is divergent, but it’s Cesaro sum is 1/2. But it seems that Grandi came with this story and explanation for solving the series: “Two brothers inherit a priceless gem from their father, whose will forbids them to sell it, so they agree that it will reside in each other’s museums on alternating years. If this agreement lasts for all eternity between the brother’s descendants, then the two families will each have half possession of the gem, even though it changes hands infinitely often.” This story was really criticized in the history, Leibniz was one of them. For more about the history of this series check: The Wikipedia page.

**2. Edgar Krahn **born on 1st October 1894 was an Estonian mathematician. He worked in many fields of math: differential geometry, differential equations, probability theory and more. He is well known for working at the Rayleigh–Faber–Krahn inequality ( mostly used in spectral geometry, you can find more here ).

**3. Dame Kathleen Mary Ollerenshaw** born on 1st October 1912 was a British mathematician and politician. She studid lattices (completed her doctorate in ‘Critical lattices’) and also most-perfect pandiagonal magic squares. She was a teacher at Manchester University and the president of the Institute of Mathematics and its Applications from 1978 to 1979. She has had an Erdős number of 5.

**4. Pierre Deligne **is a Belgian mathematician born on 3rd October 1944. He is known for work on the Weil conjectures (on generating functions derived from counting the number of points on algebraic varieties over finite fields), leading to a complete proof in 1973. What he did is considered the geometric analogue of the Riemann hypothesis. He is the winner of the 2013 Abel Prize, 2008 Wolf Prize, and 1978 Fields Medal, making him one of four mathematicians to achieve this.

**5. Louis François Antoine Arbogast **born on 4th October 1759 was a French mathematician. He wrote on series and the derivatives known by his name: he was the first writer to separate the symbols of operation from those of quantity. He also introduced the main formulas for n-order derivatives. His contributions to mathematics show him as a philosophical thinker that has to face his era. The formal algebraic manipulation of series investigated by Lagrange and Laplace in the 1770s has been put in the form of operator equalities by Arbogast in 1800. We also owe him the general concept of factorial as a product of a finite number of terms in arithmetic progression.

**6. Bernard Bolzano **born on 5th October 1781 was a Bohemian mathematician, logician, philosopher, theologian and Catholic priest.He was one of the earliest mathematicians to begin instilling rigor into mathematical analysis; he contributed the introduction of a fully rigorous ε-δ definition of a mathematical limit (Bolzano’s notion of a limit was similar to the modern one: that a limit, rather than being a relation among infinitesimals, must instead be cast in terms of how the dependent variable approaches a definite quantity as the independent variable approaches some other definite quantity). Bolzano also gave the first purely analytic proof of the fundamental theorem of algebra. Also, he is mostly remembered for the Bolzano–Weierstrass theorem (a fundamental result about convergence in a finite-dimensional Euclidean space R^n; the theorem states that each bounded sequence in R^n has a convergent subsequence).

SOOOooo… ** Let us CELEBRATE the MATHEMATICIANS born in October Together!!! **Thank you for your support and cooperation so far!

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