Explore/exploit

I am enjoying the book Algorithms to Live By. The tension between exploring and exploiting is an interesting dichotomy. For example, you decide to go out for a meal. Do you go to a restaurant that you like and is familiar? (exploit) Or, try a new restaurant? (explore) In this context, the word exploit doesn't have negative connotations, it simply means that you make a decision by exploiting (using) information that you have. By contrast, the word explore means to intentionally choose an option about which little is known. There are a number of applications discussed in the book from studies of randomized medical trials to choosing the best slot machine in a casino. While a number of variations of the explore/exploit question, often it boils down to how much time you're willing to commit to gathering information. A young person with many years of life left, is more willing to explore. An older person, with perhaps only a few years of life left, is more apt to exploit. Or, to be less morbid, if you are going to move across the country tomorrow, you're more likely to go to the restaurant that you know and love than to try a completely new restaurant on your final night in town.

There are algorithms that help you balance the explore/exploit so as to maximize payoff. After all, you may like your regular restaurant, but if you don't explore, you may never learn about the restaurant around the corner that's 10 times better! The simplest, and one of the most effective algorithms, is the win-stay, lose-switch algorithm. Exploit until you "lose", then switch to something new. Of course, real life isn't so simple, but it's a fun problem to wrestle with mathematically.

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I had Spanish class today. I'm paid up through next week. I haven't decided whether I'll continue after that even though the class does continue. Right now I'm leaning towards buying two more weeks which would put me at the week when my sister and her family arrive for their week-long visit. After that, we only have two weeks left in Spain.

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I went down to the river to take a few pictures. The moon was almost full:

Lots of rowers out:

The (best) bridge and its shadows in the evening light:

The neighborhood trash and recycling center, haha: