News
About Natalia
Games
Our Team
Articles
Gallery
Chess Links
Play Chess
Pogonina's Chess Shop
Advertise
Contact Us

Highlights

 Follow Natalia on Twitter:

http://www.pogonina.com/images//nat%20twit.jpg

 
Please help Natalia promote chess by making a donation:



 

Link to Pogonina.com





Play chess at ChessOk

365Chess.com Biggest Online Chess Games Database





Goodluckmate.com - made an easier way to find Skrill casinos

Nettikasinot.media lists the best online casinos for Finnish gamblers. For more information visit: https://www.nettikasinot.media/suomalaiset-kasinot/  

For casino and games top lists visit online casino dollar to find the news source for the gambling industry.

Sweden is now a regulated market, which means that as a player you can only play at casinos with a license. See all regulated
casinos in Sweden by Mr casinova.

To find the best casino in Norway take look at
norske casino at CasinoPiloten.

Find the best Norwegian casinobonus at NyeCasinoNorge.org.

Get exclusive access to a
huge range of free spins & no deposit casino offers with Spin Bonus.

You'll find new online casinos in Finland if you visit nettikasinot Casinokokemus

Try the exhilarating new 20p Roulette game.
Play it online at thecasinodb and find casinos to play for real money.

Get the best casino bonus information with Casino Gorilla.

Casino lovers in Finland should visit Casino PWR, a unique guide to gambling in Finnish.

Play casino in New Jersey and find the best NJ Casinos.

Online Casino
in Mexico is growing rapidly. Find the best bonuses and promotions today.

Visit SR Casino - the fastest growing comparision site for casino online.


Italian slot lovers - play Book of Ra and get the big wins.


Visit Casinomir United Kingdom for top casino sites, game guides and the best UK offers.

Chess games at Gametop

CasinoAdvisers.com For you that want to find online casino strategies, guides and a good casino bonus!

 
   ...


Polls
What's your FIDE rating?

What should Natalia do to make Pogonina.com more interesting for you?

Who is your favorite active top player?

Poker or chess: what do you like more?

What's the largest monetary chess prize you ever won?

How much time per day do you spend on chess-related activities?

Do you have a special chess mascot (pen, badge, toy, etc.)?

Which time control do you prefer for over-the-board tournaments?

The strongest women's chess team in the world is

What is the strongest national chess team in the world?

Will Magnus Carlsen's rating reach FIDE 2900?

Do you think you can become a GM?

Sunday Puzzle-45

User Rating: / 1
PoorBest 
Written by Administrator   
Sunday, 14 July 2013
Image
Puzzle courtesy of Barry R. Clarke, columnist for The Daily Telegraph and international puzzle expert

Bookmark and Share

In a wood-cutting factory, four large sawing machines stand in a windowless room. Each machine has an on/off switch attached, there being no doubt as to which switch controls which machine. Outside the door to the room are four back-up on/off switches, one for each machine inside. The power for each machine must first pass through the back-up switch, and then the machine switch before reaching the saw. The problem is, the new manager cannot decide how these back-up switches match with the machines inside the room. One day, the manager's brother visits. The manager takes him inside the sawing room where all four machines are at work and explains the problem. The brother announces that he intends to leave the room and that when he returns he will be able to match correctly the four switches outside the room to the four machines inside. The brother works alone, cannot see the machines from outside the room and solves the problem purely by operating switches. How is it possible?

Related reading:
Sunday Puzzle-44
Sunday Puzzle-43
Sunday Puzzle-42

Sunday Puzzle-41
Sunday Puzzle-40
Sunday Puzzle-39
Sunday Puzzle-38
Sunday Puzzle-37

Sunday Puzzle-36
Sunday Puzzle-35
Sunday Puzzle-34
Sunday Puzzle-33
Sunday Puzzle-32
Sunday Puzzle-31
Sunday Puzzle-30
Sunday Puzzle-29
Sunday Puzzle-28
Sunday Puzzle-27

Sunday Puzzle-26
Sunday Puzzle-25
Sunday Puzle-24
Sunday Puzzle-23
Sunday Puzzle-22
Sunday Puzzle-21
Sunday Puzzle-20
Sunday Puzzle-19
Sunday Puzzle-18

Sunday Puzzle-17
Sunday Puzzle-16
Sunday Puzzle-15
Sunday Puzzle-14
Sunday Puzzle-13
Sunday Puzzle-12
Sunday Puzzle-11
Sunday Puzzle-10

Sunday Puzzle-9
Sunday Puzzle-8
Sunday Puzzle-7
Sunday Puzzle-6
Sunday Puzzle-5
Sunday Puzzle-4
Sunday Puzzle-3
Sunday Puzzle-2

Sunday Puzzle

Bookmark and Share



Comments (1)
1. Written by frail on 05:11 15 2013 .
 
 
I assume that the machines can be heard from outside 
where the backup switches are. If so: 
 
Lets label the machines as ABCD. 
The brother turns of A&B before going outside. 
Outside, he flips switches in pairs till he 
hears complete silence. (i.e. none of the machines 
run). At this point, outside there will two 
switches that are off and two that are ON. 
The ones that are OFF correspond to machines 
C & D. So lets label them CD1 and CD2. Similarly 
the other two are labeled AB1 and AB2. Now 
the brother sets CD1 and AB1 two ON and turns 
off CD2 and AB2. He then walks back in. 
He will see one machine running. If C is 
running then CD1 = C & CD2 = D. If D is 
running then CD1 = D & CD2 = C. Thus 
he determines which switch is for C and 
which switch is for D. Now for A&B, he turns 
on machine A's switch inside. If machine A 
runs, then AB1=A & AB2=B. If not, AB1=B 
& AB2 = A.
 

Write Comment
Name:
E-mail
Homepage
Title:
BBCode:Web AddressEmail AddressBold TextItalic TextUnderlined TextQuoteCodeOpen ListList ItemClose List
Comment:



Code:* Code

Last Updated ( Sunday, 14 July 2013 )
 
< Prev   Next >