[rookie1ja]

Lion and Unicorn II. - Back to the Logic Problems
Alice came across a lion and a unicorn in a forest of forgetfulness. Those two are strange beings. The lion lies every Monday, Tuesday and Wednesday and the other days he speaks the truth. The unicorn lies on Thursdays, Fridays and Saturdays, however the other days of the week he speaks the truth.
Lion said: Yesterday I was lying and two days after tomorrow I will be lying again.
Which day did he say that?

Spoiler for Solution:

Lion and Unicorn II. - solution
This conjunction is true only if both parts are true. The first part is true only on Thursday, but the second part is a lie then (Sunday is not a lying day of the Lion). So the whole statement can never be true (at least one part is not true). Therefore the Lion could have made the statement on Monday, on Tuesday and even on Wednesday.

[quwandong]

unless i have read the question wrong i think the lion could have only made this statement on the monday.
because the lion lies on tuesday and wednesday he cannot tell the truth. but in the first part of the riddle he states " yesterday i was lying" which is true but on tuesday and wednesday he can only lie
which makes either the riddle wrong or the answer wrong
prove me wrong
Quwandong

p.s
great job on the other riddels though keep em coming

[rookie1ja]

My solution is correct because logical conjunction is true if and only if both parts of the sentence are true (and not only if one part is true as you wrote). For more check http://en.wikipedia....cal_conjunction

[shiang]

I agree with quwandon, normaly people don't have this level of logic classes. Though I understand your point of view "for a statment to be false only one part of the statment needs be false"/"for a statment to be true, all parts of a stament needs be true". However again I belive the key word here is the "lion ALWAYS lies on mon-wed" (not "the lion could lie") so all parts of the stament has to be either lies or truths to satisfy the initial contition of the problem, the lion couldn't lie or tell the truth in the same day. Of course a whole new argument could be made if the day changed as he was making the statment, but I'd rather not get into that as it probably wasn't intended by the author of this logic statment. I think your trapped in the thinkings of your logic class (I'm assuming you've taken some form of phycology, which I haven't so I really shouldn't be criticyzing you).

Quote

My solution is correct because logical conjunction is true if and only if both parts of the sentence are true (and not only if one part is true as you wrote). For more check http://en.wikipedia....cal_conjunction

[rookie1ja]

I have just found another site applying the same logic as I do - and for the same kind of puzzle. It is a difference saying 2 parts of 1 sentence and saying the same in 2 separate sentences. Check numbers 37) and 38) on page <!-- m --><a href="http://www.ocf.berkeley.edu/~yzuev/puzzles.html#alice" target="_blank">http://www.ocf.berkeley.edu/~yzuev/puzzles.html#alice</a><!-- m -->

Would be interesting to watch 2 philosophers argue about this puzzle

[Nerdess]

I can see the reasoning for your answer: since the entire statement can never be true the lion would have to say it on a lying day... and because it is the whole statement that is the lie - it doesn't matter that parts of it are true. (but I think it the most correct for the lion to say it on Monday)

If the statement was actually two statements: "Yesterday I was lying" and "2 days after tomorrow I will lie again" ... then On Tuesday and Wednesday, the lion would be lying for everything ... so the first part "yesterday I was lying..." would be a truth and not something the lion would say on those days... this would actually make the first part of the statement false -- (even though the fact itself could be true -- it is that the lion would or would not say it that is in question)... and the second part" and two days after tomorrow I will be lying again" would be would be a True statement (being a lie on a lying day for the lion). F+T=F

And in that case then only day that it would actually work is MONDAY -- the lion would be lying: so all the statement facts would be lies... yesterday (Sunday) he was NOT lying (but he would say he was) and two days after tomorrow (Thursday) he would NOT be lying again (but he would say he was)... so T+T=T

[larryhl]

Monday is the easiest answer because both parts of the sentence will be false =D But yes, any of the lying days actually work.

[Tammer]

Quote

Lion and Unicorn II. - Back to the Logic Problems
Alice came across a lion and a unicorn in a forest of forgetfulness. Those two are strange beings. The lion lies every Monday, Tuesday and Wednesday and the other days he speaks the truth. The unicorn lies on Thursdays, Fridays and Saturdays, however the other days of the week he speaks the truth.
Lion said: Yesterday I was lying and two days after tomorrow I will be lying again.
Which day did he say that?

Okay. The answer to this riddle is actually quite simple if you really think about it. The solution is Thursday. The lion says "Yesterday I was lying and two days after tomorrow I will be lying again." It says the lion lies every Monday, Tuesday and Wednesday and every other day he speaks the truth. Okay...let's break it down for all of you. Yesterday is Wednesday. The lion was lying on Wednesday. And then two days AFTER tomorrow he will be lying again. So Tomorrow being Friday...add two days (Saturday and then Sunday)...leaves Monday. The solution to the question "Which day did he say that?" is Thursday.

[larryhl]

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And then two days AFTER tomorrow he will be lying again. So Tomorrow being Friday...add two days (Saturday and then Sunday)...leaves Monday. The solution to the question "Which day did he say that?" is Thursday.

This is incorrect. Two days after tomorrow (assuming Thursday) is Sunday, not Monday...

[colorclown26]

The answer has to be monday.