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# Aliens Exist!

### #1

Posted 15 November 2007 - 09:43 AM

To help you out, Jynor gives you the following information:

Mukl is a known Fosling and Foslings always lie. In fact, only Foslings lie. Qirit is a known Arfid and Arfids always tell the truth. Also, all Arfids are Borfids. Some Borfids are Arfids, and some are Cofids. All Cofids are Borfids. All Dorfids are either Borfids or Goslings. All Goslings are Foslings, but no Foslings are Borfids. If a Dorfid is a Borfid, he’s also a Huggl.

Later that day …

A spaceship crashes to the ground followed quickly by a second. Two aliens pop out. They see you and the first yells, “Don’t shoot, I’m an Arfid!” The second yells, “Don’t shoot, I’m an Arfid!” The first yells again, “I’m also a Borfid!” The second follows with, “blast him, he’s lying, he’s a Gosling!” The first retorts, “He’s the liar, he’s a Huggl Dorfid! Shoot him!”

They both then charge toward you. Which of the two do you blast and why?

### #2

Posted 15 November 2007 - 02:15 PM

An alien, Jynor, lands and tells you that earth’s future is in your hands!

it was written in the high school men's room.Which of the two do you blast and why?

the second alien

I'll use initial letters, and denote first alien by [1] and second alien by [2].

Suppose [1] is M and [2] is Q.

Then the statements lead to this:

[1] is A, ^F, B and ^G

[2] is ^A, F, H, D -> BvG -- that is, [2] is B or [2] is G

Because No F's are B, that means [2] is G

which means .... OK I'm lost.

I think the clues aren't sufficient. Let me ask:

Does "Some Borfids are Arfids, and some are Cofids." allow for B's that are neither A nor C?

Does "only Foslings lie" and "All Goslings are Foslings" lead to a contradiction?

i.e. Goslings don't lie, because only Foslings lie, but Goslings do lie beacause they are Foslings?

This is interesting, but I'm stuck.

I'll revisit after some zzzzzzzzzzzzzzzz's

*The greatest challenge to any thinker is stating the problem in a way that will allow a solution.*

- Bertrand Russell

### #3

Posted 15 November 2007 - 08:17 PM

This is meant to exclude non-Foslings from being able to tell a lie.In fact, only Foslings lie.

### #4

Posted 16 November 2007 - 12:03 AM

BECAUSE

The first ones last sentence is " he is a liar He is a huggl dorfid shoot him.

You would not shoot a non liar if you are chasing a liar.

### #5

Posted 16 November 2007 - 01:06 AM

### #6

Posted 16 November 2007 - 02:18 AM

M is F; F iff Liar

Q is A; If A then Truthteller.

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

M will lie; Q will tell truth.

All A is B; Some B is A; Some B is C; All C is B.

All D is either B or G; All G is F; No F is B.

If DB then H.

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

Truthtellers are A, B, C and H

Liars are F and G.

D's are mixed: [B] and [G].

=============now the story==============

[1]: I am A. Innocuous. T or F.

[2]: I am A. Innocuous. T or F.

[1]: I am B. Innocuous. T or F.

[2]: [1] lies; [1] is G. Innocuous; consistent. Both T or both F.

[1]: [2] lies; [2] is H; [2] is D. Inconsistent. Cannot all be true.

[1] is M, and I shoot him.

*The greatest challenge to any thinker is stating the problem in a way that will allow a solution.*

- Bertrand Russell

### #7

Posted 16 November 2007 - 04:53 AM

### #8

Posted 16 November 2007 - 05:31 AM

I think this is very close to a solution.You shoot the first one.

BECAUSE

The first ones last sentence is " he is a liar He is a huggl dorfid shoot him.

You would not shoot a non liar if you are chasing a liar.

On first read, I didn't appreciate how close. It is the last utterance that gives it away; the rest of what's said doesn't help us.

As it stands, tho, the imperative "

**shoot him**" has no truth value, so it can't contradict anything.

But change it to a declarative "

**you should therefore shoot him**" and it becomes an incorrect conclusion for "he is a liar."

[1] thus exposes himself as the liar.

... or a poor logician ... or a good candidate for Survivor! <!-- s;) --><!-- s;) -->

*The greatest challenge to any thinker is stating the problem in a way that will allow a solution.*

- Bertrand Russell

### #9

Posted 18 November 2007 - 08:08 PM

Maybe my logic is off, as this is original work under stress of waiting for bar results

Ok, we have:

Mukl is a known Fosling and Foslings always lie. In fact, only Foslings lie. Qirit is a known Arfid and Arfids always tell the truth. Also, all Arfids are Borfids. Some Borfids are Arfids, and some are Cofids. All Cofids are Borfids. All Dorfids are either Borfids or Goslings. All Goslings are Foslings, but no Foslings are Borfids. If a Dorfid is a Borfid, he’s also a Huggl.

and

A spaceship crashes to the ground followed quickly by a second. Two aliens pop out. They see you and the first yells, “Don’t shoot, I’m an Arfid!” The second yells, “Don’t shoot, I’m an Arfid!” The first yells again, “I’m also a Borfid!” The second follows with, “blast him, he’s lying, he’s a Gosling!” The first retorts, “He’s the liar, he’s a Huggl Dorfid! Shoot him!”

We know one alien will always lie, and one will never lie.

Both say "Don't shoot I'm an arfid!" - We know one is lying and one is not. No help.

#1 is a Borfid - If he's a liar this is a lie, if he's a truth teller, it could be the truth - no help.

#2 says #1 is a Gosling and he's lying. This gets us somewhere as we know that Goslings will lie because all Goslings are Foslings and all Foslings lie. To make this statement untrue, you would have to separate the fact of being Gosling from the principal of lying. The

*and*in the sentence logically connectes the two concepts, so this must be a truth. #2 just told a truth.

But just to make it more clear, #1 says that #2 is a Huggl Dorfid and a liar. We know that if a Dorfid is a Huggl, he's also a Borfid and Borfids don't lie. #1 just told an un-truth.

We have #2 telling a truth and #1 telling an un-truth. #1 must be Mukl, so blast him!

### #10

Posted 19 November 2007 - 04:49 PM

I missed that conclusion in my solution.#2 says #1 is a Gosling and he's lying.

This gets us somewhere as we know that Goslings will lie because all Goslings are Foslings and all Foslings lie.

To make this statement untrue, you would have to separate the fact of being Gosling from the principal of lying.

Theandin the sentence logically connectes the two concepts, so this must be a truth. #2 just told a truth.

I took all the statements as red herrings except for the last one.

I guess I concluded that both of them would accuse the other, and so nothing could be made of that.

It's an interesting puzzle, and It took me awhile to understand it.

*The greatest challenge to any thinker is stating the problem in a way that will allow a solution.*

- Bertrand Russell

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