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Massimiliano Poletto
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2014 SFR Orr Springs 600K workers' ride
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The San Francisco Randonneurs series of mixed-terrain brevets has grown to include a 600Km event, the Orr Springs 600K.

With that, SFR now offers a full series of 200-600K "adventure" brevets: remote, low-traffic roads, a mix of dirt and pavement, lots of climbing, and unusual (for randonneuring) features like creek crossings and the occasional single-track.

You can read all about these 2014 rides here:
http://ridebike.org/sfr/adventure

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Today we're marking the birth of a someone who is a hero to many of us at Google. Alan Turing was born 100 years ago into a world very different from our own—but he’s a founding father of every computer and Internet company today. In 1936, his paper “On Computable Numbers”  introduced two key concepts, “algorithms” and “computing machines," which now rank among the most important intellectual breakthroughs of the 20th century.

In the evolution of computing, all paths trace back to Turing—so we're proud to help commemorate and preserve his legacy. In 2010 we helped raise funds to preserve Turing's papers at Bletchley Park, and recently we’ve worked with curators at London’s Science Museum on their new exhibition “Codebreaker - Alan Turing’s Life and Legacy.” And of course, we couldn't let this occasion pass without a doodle. If you visit our homepage today, you'll find a simulation of his “Turing machine"—try your hand at programming it, and read more about Turing in our blog post: http://goo.gl/ByYbV
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Not clear if Obama just won or lost the election (or maybe neither), but he's certainly (re-)won my respect.

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This is awesome. Wish I'd thought of it when I read that article.
This is a message in a bottle. I've got an idea for addressing a problem in Zimbabwe and no idea how to reach the people I'd like to share it with, so I'm going to see if perhaps it can propagate to them.

A couple days ago, the New York Times had an article (http://www.nytimes.com/2012/04/25/world/africa/using-us-dollars-zimbabwe-finds-a-problem-no-change.html) on an unusual problem in Zimbabwe: lack of coinage. The country has adopted the US dollar to deal with hyperinflation, and dollars are in common circulation. But coins, which are a lot heavier and harder to ship, are in short supply, which poses a problem any time people make a non-whole-dollar purchase.

One blog post (http://marketmonetarist.com/2012/04/26/good-e-money-can-solve-zimbabwes-coin-problem/) suggested a switch to electronic currency using mobile phones. I've no idea how well such technology has penetrated Zimbabwe. So I wanted to suggest a lower-tech solution.

There's a pretty simple trick, related to a lottery, for "rounding off" purchase prices that could eliminate the need for change. I've seen it in print several times, though I can't find a reference at the moment. Suppose you want to make a purchase of 33 cents. You pick a random number between 0 and 99. If the number is less than 33, you pay a dollar; otherwise you pay nothing. On average, you pay 33 cents. But in fact, you pay either 0 or 1 dollars---no coins are needed. More generally, if you owe k cents, you pay a dollar if your random number is below k; otherwise you pay nothing.

Of course, on a single purchase, you might be concerned about the possibility that you'll be overpaying by a factor of 3. Indeed, it could happen that you pay a dollar when you only owe a penny (a 1 in 100 chance). And conversely, the store owner might worry about being paid nothing. However, over a large number of purchases, these outcomes will average out---each customer will spend about as much as they were supposed to, and each store will receive about as much as it was supposed to.

To implement this, all you need is an acceptable way to generate a random number. It needs to be low tech. And it needs to be acceptable to both customer and merchant---each should be confident that the other cannot cheat them.

So here's one low-tech approach that could work. Each participant keeps a small deck of 100 cards (or other random scraps of paper) in their pocket, numbered from 0 to 99. To work out a payment, each participant reaches into their pocket, grabs a random card, and lays it face down on the table. Together, the participants then flip their cards. Compute the sum of the two numbers shown, subtract 100 if it's larger than 100, and use the resulting number (which will be between 0 and 99) as the random choice for the change protocol.

This is a good protocol because it works even if one party cheats. To see this, suppose that the customer is playing fair, and truly choosing a random 0-99 card from their pocket. Then it doesn't matter what the merchant does. For suppose the merchant chooses card k (possibly in some biased, cheating way). Then, since the customer is choosing randomly, the resulting sum is equally likely to be any on of the numbers between k and k+99. Once we subtract 100 from the larger outcomes, we find all numbers between 0 and 99 equally likely, as desired.

As a simplification, note that the customer can make their choice at home, putting just a few random cards (or, just as effective, a few scraps of paper with random numbers written on them) in their pocket in the morning and using them for the days purchases. So long as they don't purchase from the same merchant twice, the merchant has no information they can use to cheat the customer (conversely, if a customer returns and uses the same card, a cheating merchant can take advantage of that knowledge to ensure they get paid). As another variant, the merchant could keep two decks, one to be used by the customer and one by the merchant. The customer will want to inspect their deck, but this would be pretty easy if the cards were kept sorted.

Is this practical? I'm not sure. But the "only" thing it needs is some paper. Plus some basic mathematical skill, but, importantly, the same mathematical skill needed to compute the cost of two items---a skill I think we can safely assume of anyone who is making purchases.

I'd love to float this idea past someone closer to Zimbabwe, who might be able to comment on its feasibility. If you know someone, please pass it on!

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There’s been a lot of buzz...so I’m excited to officially introduce Google Drive. We have really focused here on letting users create & share with others and this is a natural evolution of Google Docs. It’s not just storage, it’s about helping you live and work in the cloud and making sure your data is seamlessly available everywhere. You can use it across platforms -- Mac, PC, Android, iOS (coming soon) -- and you can use it with many third party applications - we’re working with many developers to expand the Drive ecosystem.

So, between the Loch Ness Monster and Google Drive, looks like you’ll have to keep looking for Nessie.

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The San Francisco Randonneurs Adventure Series is here! Dirt roads, lots of climbing, low traffic, beautiful views.

Consider joining us this summer for epic bike rides of 200, 300, and 400Km.

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Originally shared by ****
Thank you +Gmail team for the best service ever. you truly saved my life with your brilliant engineering. My father is a well-respected member in an institute. His email(which was a Gmail account) was hacked & all of his contacts were spammed with scam email asking for money. Once I received that malicious email from dad i knew something was wrong. I tried entering his account & as expected the password has been changed.

Well.. Get ready, because here starts the brilliance of the Gmail team. When i entered a wrong password there was a notification informing me that the password for this account has changed in the last hour!!!!. I tried to restore the password & surprise surprise... the hacker changed the recovery email and recovery phone number which means there is no way i can access my email again right? GUESS AGAIN. Because Gmail noticed these sudden changes it offered me to send me a recovery code using the old phone number which was as i mentioned deleted. This smart idea saved my life and saved important information that is simply priceless. So, with the help of the +Gmail team I recovered my dad's email account and have the hacker's email and phone number (I'll have fun with these).

The brilliance of the +Gmail team does not stop here. The first notification i received when i accessed the inbox for the first time was that all my emails were forwarded to the hackers email & because of that notification I stopped any future email from being forwarded. Finally, to maximize our security I activated the 2-step verification using my +Android device. Now even if someone has my password, he simply cannot access the account unless he has my Android device as well.

Once again, I simply cannot thank you enough. Thank you +Google, +Google Developers and thank you +Gmail team for this excellent product that makes our lives in the web more secure.

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Interesting paper on GPS spoofing that may explain how Iran brought down the US reconnaissance drone without damaging it.

(More background at http://www.theregister.co.uk/2011/12/15/us_spy_drone_gps_spoofing/)
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