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8/1/2012 11:08:45 AM

LittleReg1
LittleReg1
Posts: 3
Whenever I search the Internet for help solving Logic Problems, all I ever find are the typical 'mechanics' explanations. I am well-familiar with these. The help I need is in the realm of the 'back page' puzzles - the ones that seem to use some sort of 'super logic' in order to solve them. In the usual format, the puzzles gradually get more difficult as you work your way through the puzzles in numerical order. I can tell when I'm starting into the 'master section' when I notice in the solutions that logical constructs are based upon the dreaded "couldn't be placed" condition.

I understand that the investigative process requires eliminating possibilities that contain a group of facts rather than just one, but where I get stuck is when the puzzles reach a level of difficulty where I simply can't figure out where to start investigating the possibilities. In the simpler puzzles, the thought processes can get quite challenging, but at least you know most of the time where each step of the investigation leads, or with only a few possibilities to examine. Keep in mind that the linear, 'vertical' analysis can get deep, but at least you're not presented with a plethora of choices.

The problem I have is when I check the solution of a problem I'm stuck on, very early on in the detail (many times immediately after the 'given' information is listed), there is a thought process provided that, when I examine it, is certainly correct, but my question is: how did the 'solver' know to go there as opposed to a wide variety of other starting points? No instruction is ever provided as to why the 'solver' chose this particular path against all the others. Is it simply intuition or creativity, or is there a sort of 'super-logic' skill that must be developed that eliminates many of the other possibilities?

This problem is particularly acute in the 'table' and 'diagram' puzzles. How did the 'solver' know to begin the way it did?

I see that there are others in this forum who have noted that guessing is required for advanced puzzles - is this true? I hope not. I see all logic puzzles - even the most difficult ones - as a matter of analysis, like in the game of chess. In other words, you may have to select from a number of choices, but you will be able to see once you've reached the end of your investigation that your choice is the correct one and not have to simply cross your fingers and hope.

If there's anyone in this board who can describe this 'super logic' process and can provide a methodology as to how the 'solver' has selected the paths that it has for the advanced puzzles, I would be greatly appreciative! Thanks.

8/1/2012 2:26:09 PM

Frances
Frances
Posts: 698
Hi LittleReg1,
You have written an intelligent and articulate post that mirrors my thoughts---but better expressed than I could have done. I don't have any answers. Sometimes I wonder if the solutions to these hard logics are written with hindsight, that is the author knows which piece of information or logic will continue the solving process as the other options and scenarios have already been explored and eliminated.

Frances.

8/1/2012 4:53:41 PM

Amy Lowenstein
Amy Lowenstein
Posts: 1599
I agree with you, Frances. I suspect the constructor had something in mind, and therefore started with what they knew would be the best place to start. In fact, sometimes they go in a cockamamie order (if you ask me) just to exhaust all the "wrong" possibilities first. For example, they might have a paragraph which goes something like "Jamie married either Rebecca, Sharon or Theresa. If he had married Rebecca, then [a long series of events, which are finally disproved]." Now, at this point, if I personally were doing the puzzle and had started with testing whom Jamie married, and then I found that Rebecca couldn't possibly be his bride, I'd next go on to Sharon, the alphabetically next person, the logical (in my opinion) place to continue. But no, the author continues with something like, "If he had married Theresa, then [another long series of events, which are finally disproved]." Then the author will go on with "Therefore, Sharon is the only choice left."

So, OK, the author proves the choices of Rebecca and Theresa both lead to dead ends, but who would really try to solve a puzzle by picking the first alternative, then the 3rd alternative? I wouldn't. I'd appreciate it more if the author would say "If you then assume Jamie married Sharon, you don't get any dead ends. It's probably the right choice. But just to make sure, temporarily assume he married Theresa. Then you'll find [the long scenario which finally disproves Theresa]."

--
Amy

8/1/2012 5:21:34 PM

Purple Pisces
Purple Pisces
Posts: 878
Welcome LittleReg1! I don't have an answer for you but would like to know as well! I keep hoping that each time I solve a tough logic problem, especially the "if this, then that" kind, I'll find that magic trick that will bring some insight into how to solve them. One thing I don't do that I probably should start is to read the solution in the back of the book to see if that brings any further insight. I'm just so happy when I solve it that I move onto the next one.

I've posted this on another thread before but it fits here too: I've always wondered how logic puzzle constructors can write clues that give us just the right amount of info we need without making it too easy. Seems like a more difficult task than solving the puzzle, to me anyway.

8/2/2012 10:54:39 AM

LittleReg1
LittleReg1
Posts: 3
Good takes! I see that I am not alone. I sincerely hope that the solutions are not rationalized, as is inferred as a possibility by some of you. Maybe a puzzle author will check in to this blog one of these days and provide us with these advance solving techniques. I'll admit that I've had a few "DOH!" moments when examining the solutions, but more often than not, I just can't see why the solution chooses a particular path.

An example of the 'supposition' style of the solution is when it refers directly to an individual number's set of clues. Using Amy's example, the solution might say "Jamie did not marry Rebecca (3)", which refers to a portion of Clue #3 that says "Jamie did not marry anyone with a 'c' in her name." This is what I call a 'one-off' reference, which stands in contrast to a statement which is direct: "Jamie did not marry Rebecca." However, I've noticed that the solutions will many times make two- and even three-off references, but still only place the original clue in parentheses as if the reasoning were a given.

The reason I'm bringing this up is because I believe that it shows - even in the simplest of cases - that the solution authors will make suppositions, not realizing that there are consequences to their statements. For example, I have given the solutions the benefit of the doubt regarding these references, only to search and search, not being able to discover how they believed that the clue is a direct reference to a conclusion. This has led me down dead-end paths of investigation that I never would have chosen, otherwise.

Those of you who have taken formal logic courses know that deductive logic can be diagrammed. I think that if the solution authors followed one of the traditional systems of plotting the premises, they would find that they may have 'jumped the river without building the bridge.'

8/2/2012 11:53:24 AM

Amy Lowenstein
Amy Lowenstein
Posts: 1599
When I solve a puzzle, I often cross things off with a reference to the clue number. Sometimes, it's a combination of two clue numbers, not just 1, which means that "Jamie didn't marry Rebecca." And I'll put an X in the "Jamie / Rebecca" square with little number such as "5,10." Then I know I used clues 5 & 10 to come to that conclusion. When the back of the book just says that clue 10, or clue 5, rules out Jamie and Rebecca, that bothers me, too, Reg.

--
Amy

8/3/2012 12:38:10 PM

LittleReg1
LittleReg1
Posts: 3
Nice use of commas, Amy! smile

8/3/2012 5:05:40 PM

Amy Lowenstein
Amy Lowenstein
Posts: 1599
Thanks, Reg. I'll take praise wherever I can get it.

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Amy

11/11/2012 2:29:52 AM

KS Granny
KS Granny
Posts: 1
So it's not just me! I pride myself on my logical thinking, took logic in college, everyone says I'm logical...so how come I can't solve these puzzles? I bought a book of Dell Logic Puzzles, figuring it would be like Sudoku and the first third or so would be easy so I could figure out how they work. Well, the first two puzzles were easy...the third, fourth, fifth, and sixth were impossible. I gave up. *sigh*

11/11/2012 9:53:47 AM

Amy Lowenstein
Amy Lowenstein
Posts: 1599
I never do any Sudoku's, Granny, but I usually find that on the regular logic puzzles, Dell's are easier in the beginning of the book and harder at the end (though not always). I appreciate Dell's system of putting a number of stars on them (although sometimes I get stumped on the 1-star puzzles that don't have a grid, but occasionally I can answer a 5-star puzzle that DOES have a grid).

I usually work the Dell logic puzzles. Within the last year I took advantage of a great offer where you could get 28 varied logic books for one low price, so I'm now working my way thru some of those books. Some of them are Penny books. I must opine, though, that the explanations in the back of the Penny books, get so abbreviated that it boggles my mind. At least the Dell books have long-winded explanations in complete sentences.

What bothers me about both of them, though, is that they cram whatever they're saying, onto the fewest possible pages, thus ignoring the idea of paragraphs (which in my opinion would make the answers a LOT easier to read).

There was one puzzle in the back of one of those "special" books, which puzzle I liked so much (it had to do with 18 guys who play baseball) that I decided to keep my own version of it for the future. I typed everything out in a Microsoft Word document, and I put plenty of paragraph space between sentences of the explanation. In some future year when I go to do that puzzle based on my rewriting of it in that Word document, I won't have any trouble following the answers.

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Amy

11/20/2012 10:43:18 AM

yanks5179
yanks5179
Posts: 6
You echo my thoughts exactly.

The puzzles, at a point, stop being logic puzzles and become trial and error puzzles. A logic puzzle should be entirely based on logic and deduction, not hoping to stumble into the correct starting point. Some puzzles have paths that make you do virtually the entire puzzle before realizing a contradiction and making you go back to basics (ie, the work you've done after the clues) and start again to try and plug the next variable in. Reading the answers in the backs of the book, they tell you where they start, but not why of all the blank boxes and permutations they began there. Sometimes it's a bit obvious. If one term kept getting used and you only have two "open" boxes on them then that's often a good starting place. But when you turn to the back and see a full page of explanation of why one answer was wrong, it shows that you have to do the ENTIRE puzzle sometimes to get to that point, then jump to another plug and play. To me, it sucks the fun out of logic and deduction when it becomes a game you don't have to be good at--anyone can play trial and error; it takes no skill. Glad to know I'm not alone in this.

11/20/2012 5:43:05 PM

Amy Lowenstein
Amy Lowenstein
Posts: 1599
I do usually try to find (and write down on scrap paper) what the two-way guesses are. Once in a while, just my writing down all the 2-ways makes it obvious to me that one thing can't possibly be such-and-such. Then again, sometimes no such thing leaps off the page at me, but at least I see a set of possibilities, and if I try one thing and it doesn't work, then the other must be so. If I try something and it does work up to a point, I keep in mind that MAYBE it's right.

--
Amy

11/24/2012 11:46:05 AM

Semipro
Semipro
Posts: 292
My impression--the solutions are written so as to be as compact as possible, and their purpose is to prove the solution right, rather than to explain how to get there. Anyway, a given problem may have several possible starting points and paths to completion. An official solution would describe just one way, and some solvers would have taken another.

If you were teaching someone how to solve logic problems, you'd do it very differently.

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