I'm trying an experiment. I'll write a few blog posts in English and I ask you to use English in the comments as well. Hope it goes well.

_I'm trying an experiment. I'll write a few blog posts in English and I ask you to use English in the comments as well. Hope it goes well._

Here's a synchronization puzzle that's somewhat classic but is very neat:

_Here's a synchronization puzzle that's somewhat classic but is very neat:_

bq. You are one of P recently arrested prisoners. The warden, a deranged computer scientist, makes the following announcement:
You may meet together today and plan a strategy, but after today you will be in isolated cells and have no communication with one another.

* Devise a winning strategy when you know that the initial state of the switch is off.
* Devise a winning strategy when you do not know whether the initial state of the switch is on or off.

As always, if you've seen the puzzle before please don't spoil it.

_As always, if you've seen the puzzle before please don't spoil it._