Five men and five dogs (each man owned a dog) went hiking. They encountered a river that was swift and deep. The only way to cross it was an abandoned boat, left ashore on their side. But it would only hold three living things. Unfortunately, the dogs were edgy and could not be near another person (not even momentarily) unless its owner was present. One of the dogs attended a highly advanced, highly specialized obedience school and therefore knew how to operate the boat -- the other dogs lack this skill. How did the five men and the five dogs cross the river?
This one will probably give you a headache.
Post Scriptum: it will be easier for you if you name the five men A, B, C, D, E and the dogs a, b, c, d, e. A is the owner of a; B is the owner of b; C is the owner of c; etc.
In other words, in the presence of other people, a dog cannot be without it's master, neither on the boat nor at the banks of the river? Not even that highly trained, obedient dog capable of operating the boat? (btw, that's a cool dog)
As long as no other people are there, a dog has no problems being with other dogs, even if it's master is not present?
Last edited by ayw on February 19th, 2009, 11:05 pm, edited 1 time in total.
ayw wrote:
In other words, in the presence of other people, a dog cannot be without it's master, neither on the boat nor at the banks of the river? Not even that highly trained, obedient dog capable of operating the boat? (btw, that's a cool dog)
As long as no other people are there, a dog has no problems being with other dogs, even if it's master is not present?
Two Question. Can all dogs operate a boat or just a single Dog? And is the river too swiff for a dog to swim attached to rope with the owner in the boat?
I just made A B C D E and @ (special dog) b c d e out of paper, moving them back and forward (while listening to B'z )... working on it
EDIT (15min later)
if the special dog @ is alone at one shore and three people B, C and D arrive in the boat, can they get off and the dog on on the boat or does that fall in the category of a dog without owner???
Last edited by Sayumi on February 20th, 2009, 1:59 pm, edited 1 time in total.
"It is one of those instances where the reasoner can produce an effect which seems remarkable to his neighbor, because the latter has missed the one little point which is the basis of the deduction."
Sherlock Holmes
sstimson: Only the special dog can operate the boat. The only way to cross the river is by boat, other ways are denied.
Sayumi: Quite unnexpecting that you don't know the answer You're always the first one to get it. But, this one is difficult. What you say is correct, it falls in the category of a dog without owner.
Keep your brains working everyone, and I'm sure you'll get the answer correctly.
Tricky. Like Sayumi, I resorted to paper cutouts of the dogs and owners. If I understood the rules correctly then the following should work...
Spoiler:
First, have each owner take their dog to the other side and return. Then three owners, but not that of the special dog, cross to the other side and have the special dog return with the ownerless dog from the other side. The owner of the special dog crosses with the other owner and his dog, then returns to get his special dog.
Graphically this would look like...
Spoiler:
Following Sayumi's notation, ABCDE are the owners of dogs @bcde, respectively, where @ is the special dog.
@ayw I came up with something similar, but you can't have the owners of the others boats getting of and the special dog getting on because in that moment the special dog and one other would be without their owners... (CDE getting off and @b getting on the boat)
Holmes wrote:
Sayumi: Quite unnexpecting that you don't know the answer You're always the first one to get it. But, this one is difficult. What you say is correct, it falls in the category of a dog without owner.
lol... I' still working on it, but I'm kinda stuck at the moment. I can get 2dogs and 2owners to the other side (not the special dog), but after that... well it's Saturday, so I'll have lots of free time
but another question : it should be okay to have BC at one side and @bc arriving in the boat with just bc getting off and @ returning in the boat, right (because @ doesn't leave the boat so he doesn't really meet the other owners) ? Because if @ couldn't even be in the boat without it's owner while people are on the shore I would start thinking it's impossible....
"It is one of those instances where the reasoner can produce an effect which seems remarkable to his neighbor, because the latter has missed the one little point which is the basis of the deduction."
Sherlock Holmes
Sayumi wrote:
@ayw I came up with something similar, but you can't have the owners of the others boats getting of and the special dog getting on because in that moment the special dog and one other would be without their owners... (CDE getting off and @b getting on the boat)
True, but I have a feeling that it is necessary to have at least one transition of that sort.
I can see, however, the difference in "danger" between the above and, e.g., ...
Sayumi wrote: ...having BC at one side and @bc arriving in the boat with just bc getting off and @ returning in the boat
We will need Holmes to resolve this important technicality. In the meantime, back to the paper cut-outs...
blurfbreg : Of course humans can control the boat. kat1214young : The special dog doesn't need to be in the boat all times, it can go and resturn as he wishes, but always, if there are other humans, with its master. What you say isa correct: 1 boat, three living things. Sayumi and ayw: What you say seems impossible, but there is a way to change this impossible to possible.
HINT!: Humans can control the boat, everyone knows, what if the master and his dog cross together? Also, for this problem, there are three combinations of crossing the river:special dog with other dogs, humans with humans and master with his own dog.
1st trip = A+a+B then drop A and a
2nd trip = B+b C then drop B and b
3rd trip = C+c+D then drop C+c
4th trip = D+d+E then drop D+d
5th trip = E goes back to get e
it didn't say that the dogs can't be left alone on the other side without their master since there are other dogs on that side
*
)... working on it 
