[bonanova]

Four young couples go for a stroll and come upon a river.

They find a boat, able to carry two persons at a time.

The girls, of course can row.

But there is a problem: the girls are extremely jealous.

So there is an agreement:

No girl may stay be in the company of another's boy friend unless her own b/f is present as well.

How do they all get across? They can't.

But one of the boys spots a small island in the river,

which can be used for intermediate loading and unloading.

Now is it possible?

[bonanova]

Variation on my first answer, no island.

GF1 brings BF1 across - sails back.

GF2 brings GF1 across - sails back.

GF2 brings BF2 across - sails back.

GF3 brings GF2 across - sails back.

GF3 brings BF3 across - sails back.

GF4 brings GF3 across - sails back.

GF4 brings BF4 across.

I have not yet sunk to little markers.

You say

GF1 brings BF1 across - sails back.

At this point GF1 is with the other boys, and her BF is no where to be seen.

I'll lend you 44 cents if you like.

[Guest]

You say

GF1 brings BF1 across - sails back.

At this point GF1 is with the other boys, and her BF is no where to be seen.

I'll lend you 44 cents if you like.

Ahh yes, but she doesn't "stay in the company of another's boy friend". In fact she heads right back out again with the other girl. She doesn't even have to get out of the boat.

[bonanova]

Ahh yes, but she doesn't "stay in the company of another's boy friend". In fact she heads right back out again with the other girl. She doesn't even have to get out of the boat.

You got me. I meant the more stringent case of being in male company w/o own bf.

I've edited the OP.

[Guest]

You say

a2 goes to the island and gives the bout to c2.

At this point haven't you have left b2 with a1 on the coast?

ok, then it could be b2 who goes for her b1 and brings him to the coust, then comes to an island- and then again back to chain...will it work?

[Guest]

You say

a2 goes to the island and gives the bout to c2.

At this point haven't you have left b2 with a1 on the coast?

ok, i have checked it once more- you have missed the step- a1 goes on boat and brings b1 and then a2 goes to island with girls- so we have b1 and b2 together with a1

[Guest]

You got me. I meant the more stringent case of being in male company w/o own bf.

I've edited the OP.

In most of these problems that I have seen, this isn't a factor, but I will accept it and work around it. Here are some inescapable consequences, as far as I can tell.

There can never be more than two girls stranded alone anywhere. If there are, a girl would have to come remedy the situation.

The first boat: must either be a GF-BF pair, or two GFs.

if it is a GF-BF pair, it must be the boy that sails back, if it is two girls either one can sail back so....

There is at least one situation with a lone girl stranded somewhere, with everything else back home.

Once this happens, it is unacceptable for two boys to leave. It is unacceptable for a boy to leave without his GF. The solo boy cannot leave, because he cannot take another boy and he cannot take another girl.

As of this point things get more complicated -> two branches, with lots of twigs.

1. BF-GF sail off. They cannot visit the same location as the first stranded girl, and the girl cannot come back, so the boy must deposit her alone in the other remote location.

Now there are two solo guys and two pairs back home.

2. GFs sail off. They can go anywhere, and you have two stranded girls in some configuration.

Again, two solo guys and two pairs back home.

So for the possibilities: Everyone is back home in all cases, except two girls.

And that is how every problem must start.

[bonanova]

ok, i have checked it once more- you have missed the step- a1 goes on boat and brings b1 and then a2 goes to island with girls- so we have b1 and b2 together with a1

You're right ... a 21-move solution.

My bad.

[bonanova]

Variation on my first answer, no island.

GF1 brings BF1 across - sails back.

GF2 brings GF1 across - sails back.

GF2 brings BF2 across - sails back.

GF3 brings GF2 across - sails back.

GF3 brings BF3 across - sails back.

GF4 brings GF3 across - sails back.

GF4 brings BF4 across.

I have not yet sunk to little markers.

Sorry, I quoted the wrong step. I meant to call your attention to this one:

GF3 brings GF2 across - sails back.

After this step, you have BF2,3,4 with GF3,4 on the near shore. That's ok.

And BF1 with GF1,2 on the far shore. That's a no-no.

When GF3 was sailed back, GF2 was with BF1 without BF2.

And after the next step, GF2,3 are with BF1 without their BF's.

-------------

There is a 17-move solution that obeys both the strict and the relaxed versions of the requirement.

[Guest]

There is a 17-move solution that obeys both the strict and the relaxed versions of the requirement.

Gawd, bonanova, you are so anal about this one

GF2 brings GF1 to island, sails back.

GF3 brings GF2 to island, sails back.

BF+GF 3 go to other side, BF3 sails back.

BF3 brings BF2 to other side, BF2 sails back.

BF2 brings BF1 to other side, BF1 sails back.

BF1 brings BF4 to other side.

GF3 retrieves last three girls one by one (6 steps total).

17 steps. Follows rules, I think...

[Guest]

BN had a ferry bad experience - give the grand pzzl master a brk - anyway it's more fun (from where i'm sitting)

[Guest]

Haha, this has been a very painful experience for me.