Martingales and Stopping
What a fair game permits, and when to walk away.
From the editor · Issue 01
The price of waiting
A fair game can still be a bad way to spend an afternoon. Our opening essay asks what happens when you may choose the moment to stop: which guarantees survive that freedom, and which quietly disappear.
The question travels well. In probability it becomes a stopping time; in computing, a rule for making a decision with incomplete information; in finance, the right to exercise an option. Castalia follows these connections through the assumptions that make them work. We begin with one finished essay. There is no prize for filling the shelf.
The reading room
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Published essays
- Pieces
- 1
- Minutes
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Why these connect
The same question can need a proof, an algorithm and a price. These are the conversations we want to follow.
- Mathematics
- What can we guarantee when the next observation is unknown?
- Computer science
- How do we turn a decision rule into a procedure that actually terminates?
- Finance
- What is the freedom to wait worth, and who pays for it?
- Economics
- How do those individual choices change when everyone else is choosing too?