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a secretary problem with maximum ability

April 27, 2017
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a secretary problem with maximum ability

The Riddler of today has a secretary problem, where one measures sequentially N random variables until one deems the current variable to be the largest of the whole sample. The classical secretary problem has a counter-intuitive solution where one first measures N/e random variables without taking any decision and then and only then picks the […]

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Le Monde puzzle [#1003]

April 17, 2017
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Le Monde puzzle [#1003]

A purely arithmetic Le Monde mathematical puzzle: Find the four integers w, x, y, z such that the four smallest pairwise sums among the six pairwise sums are 59, 65, 66, and 69. Similarly, find the four smallest of the five integers v, x, y, z such that the five smallest pairwise sums among the […]

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optimultiplication [a riddle]

April 13, 2017
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optimultiplication [a riddle]

The riddle of this week is about an optimisation of positioning the four digits of a multiplication of two numbers with two digits each and is open to a coding resolution: Four digits are drawn without replacement from {0,1,…,9}, one at a time. What is the optimal strategy to position those four digits, two digits […]

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optimultiplication [a riddle]

April 13, 2017
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optimultiplication [a riddle]

The riddle of this week is about an optimisation of positioning the four digits of a multiplication of two numbers with two digits each and is open to a coding resolution: Four digits are drawn without replacement from {0,1,…,9}, one at a time. What is the optimal strategy to position those four digits, two digits […]

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optimultiplication [a riddle]

April 13, 2017
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optimultiplication [a riddle]

The riddle of this week is about an optimisation of positioning the four digits of a multiplication of two numbers with two digits each and is open to a coding resolution: Four digits are drawn without replacement from {0,1,…,9}, one at a time. What is the optimal strategy to position those four digits, two digits […]

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Statlearn17, Lyon

April 6, 2017
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Statlearn17, Lyon

Today and tomorrow, I am attending the Statlearn17 conference in Lyon, France. Which is a workshop with one-hour talks on statistics and machine learning. And which makes for the second workshop on machine learning in two weeks! Yesterday there were two tutorials in R, but I only took the train to Lyon this morning: it […]

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Le Monde puzzle [#1002]

April 3, 2017
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Le Monde puzzle [#1002]

For once and only because it is part of this competition, a geometric Le Monde mathematical puzzle: Given both diagonals of lengths p=105 and q=116, what is the parallelogram with the largest area? and when the perimeter is furthermore constrained to be L=290? This made me jump right away to the quadrilateral page on Wikipedia, […]

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Le Monde puzzle [#1000…1025]

March 27, 2017
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Le Monde puzzle [#1000…1025]

Le Monde mathematical puzzle launched a competition to celebrate its 1000th puzzle! A fairly long-term competition as it runs over the 25 coming puzzles (and hence weeks). Starting with puzzle #1001. Here is the 1000th puzzle, not part of the competition: Alice & Bob spend five (identical) vouchers in five different shops, each time buying […]

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Le Monde puzzle [#1001]

March 26, 2017
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Le Monde puzzle [#1001]

After a long lag (due to my missing the free copies distributed at Paris-Dauphine!), here is a Sudoku-like Le Monde mathematical puzzle: A grid of size (n,n) holds integer values such that any entry larger than 1 is the sum of one term in the same column and one term in the same row. What […]

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what does more efficient Monte Carlo mean?

March 16, 2017
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what does more efficient Monte Carlo mean?

“I was just thinking that there might be a magic trick to simulate directly from this distribution without having to go for less efficient methods.” In a simple question on X validated a few days ago [about simulating from x²φ(x)] popped up the remark that the person asking the question wanted a direct simulation method […]

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