One powerful tool in the theory of enumeration as well as in prime number theory is the inclusion-exclusion principle (sieve of Erathosthenes). This relates the cardinality of the union of certain sets to the cardinalities of the intersections of some of them, these latter cardinalities often being easier to handle. 506 more words

## Tag » Eratosthenes

#### Sieve of Eratosthenes

everybody has already read about the the ancient Greek mathematician Eratosthenes (250 BCE). A basic algorithm could be found at http://en.wikipedia.org/wiki/Sieve_of_Eratosthenes

but why in the optimizing algorithm, the variable i should not exceed square root of n ? 113 more words

#### The Dog-Star: Dionysus, Ikarios and a Daughter's Dog ( D Scholia, Il. 22.29)

“**Of Orion**: calls this, then, the dog-star. Some say that this dog transformed into a star is not Orion’s but instead is Erigonê’s, and that it was made into a star for the following reason. 196 more words

#### #10 From Classical Beginnings

The classical Greek astronomers between 624 BCE and the 12oo’s CE did not consider themselves scientists. Astronomy was considered more of a philosophy than a science. 2.136 more words

#### TED moments!

We love TED, it shares new ideas based on the activity of renown scientists, economists, artists, etc… It makes knowledge more accessible so we are proud to everyday share with you a TED video. 131 more words

#### Go Visit Your Child’s Class

This afternoon I spent a couple hours with #2’s class. Her class is learning about ancient Greece, so I offered to design a little project so they could calculate the size of a ball, the same way… 600 more words

#### Another Mathematical Observation

I haven’t posted in a little while, but I’ve got some new juicy stuff here for you, so enjoy!

Continuing on from the article I wrote a few days back ( 608 more words