Pure maths, physics, logic (braingames.ru): non-trade-related brain games - page 131

 
TheXpert:
I have an endless supply of it...
Try it :/
 
OK, someone write a simple strategy for 20-30 metres and we'll see.
 
TheXpert:
Okay, someone write a simple strategy for 20-30 meters, then we'll see.

well you can start with an easy one, a corridor of almost 30 metres:

1) pass corridor 1 completely and return to the centre

2) Walked 19.(9) metres along corridor 2 and went straight back to the centre (if it is empty). If there was a perpetrator in it, we would have seen him

3) While we were walking those 20 meters there and back, the occupant would not have had time to escape unnoticed into another corridor and get far away.

so

4a) we'll see him running down corridor 1 and go after him.

4b) we don't see him, so he's in corridor 3 and we go get him.

 
Ah, that's it, I've realised the error of my reasoning. Everything was thinking right, except for one thing.
 
TheXpert: Ah, that's it, I got it wrong in my reasoning. Everything was thinking right, except for one thing.

I don't get it, I've got infinity too so far...

But the moderator says it's a mistake.

I don't want to go down different corridors. You can cut one off right away by just going all the way down it. I don't care where the occupant runs the whole time.

 
Mathemat:

I don't get it, I've got infinity too so far...

But the moderator says it's a mistake.

I don't want to go down different corridors. One can be cut off at once.

at once, but not forever, with infinity.
 

My reasoning was based on the sequence of the occupier. Apparently it is incorrect.

 
This is where it all makes sense from here. There's a convergent sequence there.
 
Mischek: And how many ?

Mischa, wait, I really want to solve it on my own.

TheXpert: That' s where it all makes sense from here. There's a convergent sequence there.

I can't see it yet. I'm still having a breakdown.

And anyway,

2) walked 19.(9) metres down corridor 2 and went straight back to the centre (if it's empty). If there was a perpetrator in it, we would have seen him
40 metres of reserve means that we have already calculated that the perpetrator would probably be no closer than 20 metres to the room - if the MM is in it.
 
Nah, I'll pass (for now), I'm maxing out at 50.