#21




That Mateo puzzle
I remember spending a lot of time and paper on a puzzle involving Mateo.
It was really difficult. I think it had a lot of clues of my favorite form: "Of A and B, blah blah." You will probably have to make several passes through the clues as you extract everything you can from clues of that form. Basically, you have to keep going through the clues until you make a pass without adding any additional Xs. If there are clues where category members are a fixed distance from each other in the same category and there are only two choices left for each, remember to X out the overlapping cells for the other members. If there are multiple ordering clues that involve the same category member, remember to X out the members at the ends. E.g. if A < B and B < C, then A cannot be C. If you have a lot of Xs, then this puzzle is probably be solved by looking at pairwise intersections of rows and columns in different categories. Anywhere you find a null intersection, you can place an X somewhere. Hopefully it will be a new one that you don't already have. Oh, and remember to place all the Xs for the "Either..." and "Neither ..." clues. E.g. Either A or B is blah. A and B aren't the same person, so if they aren't in the same category, remember to X out their intersection. If this doesn't get you to that first positive, then post the info, and I'll see if I can get you there. Last edited by zenobia43; 06162012 at 01:46 AM. 
#22




Monday
Tuesday Wednesday Thursday Friday First Names Elliott Erika Lukas Mateo Zoey Tape duct tape masking tape painters tape paper tape scotch tape Coffees Colombian Harrar Sidamo Toraja Kalossi Yirgacheffe 1. Of the person who brewed the Toraja Kalossi coffee and the person who bought masking tape, one is Mateo and the other is Elliott. 2. The person who bought scotch tape arrived the day after the person who bought duct tape. 3. Of the person who brewed the Harrar coffee and the person who arrived on Wednesday, one is Zoey and the other bought masking tape. 4. Neither the person who brewed the Colombian coffee nor the person who bought painters tape arrived on Wednesday. 5. Of the person who arrived on Tuesday and the person who brewed the Sidamo coffee, one is Erika and the other bought masking tape. 6. The person who bought duct tape arrived the day after Mateo. 7. The person who arrived on Monday didn't buy painters tape. 8. Of the person who arrived on Wednesday and the person who bought scotch tape, one brewed the Yirgacheffe coffee and the other is Elliott. Hi again Zenobia43. I've been trying with this one for well over 6hrs. I will post another below what my thinking is on it. Stan 
#23




So far I have Harrar coffee = Tuesday. Sidamo coffee Wednesday. Papertape = Monday.
Harrar coffee = Tuesday. Sidamo coffee= Wednesday because Masking tape is Wed or Harrar coffee, clue 3 or Tues Sidamo coffee. Masking tape cannot be Tues and Wed Masking tape cannot be Sidamo and Harrar So Masking tape must either be Tuesday and Harrar or Wednesday and Sidamo. Sidamo not Tuesday clue 5. so must be wed. We also have Erika either Tues or Wed Clue 5 5. Of the person who arrived on Tuesday and the person who brewed the Sidamo coffee, one is Erika and the other bought masking tape. So Masking tape is Tues or Wed Zoey is Tues or Wed clue 3 Of the person who brewed the Harrar coffee and the person who arrived on Wednesday, one is Zoey and the other bought masking tape So we have Zoey and Erika Tues or wed. But Mateo is Tuesday or Wednesday, because he is one day before The person Duct taped and they are one day before Scotch tape. Scotch tape has to be either Thurs or frid. and Mateo has to be tuesday or Wednesday. Mateo cannot be Monday as that would mean Scotch tape would have to be Wednesday and clue 88. Of the person who arrived on Wednesday and the person who bought scotch tape, one brewed the Yirgacheffe coffee and the other is Elliott. Therein lies my problem It's either a very hard puzzle or it's wrong. Stan 
#24




Elliott  Erika
It is a very difficult puzzle in my opinion.
Part of your solution is correct, but there is a flaw in your logic that has sent you down a dead end. Repeating from your post: Clue 3: Masking tape is Wednesday or Harrar. This also implies that Harrar cannot be Wednesday. Clue 5: Masking tape is Tuesday or Sidamo. This also implies that Sidamo cannot be Tuesday. So you are correct when you state "So Masking tape must either be Tuesday and Harrar or Wednesday and Sidamo." However, your next statement is incorrect: "Sidamo not Tuesday clue 5. so must be Wed. " Clues 3 and 5 present two possible associations for masking tape. Just because masking tape is one of those two associations, it doesn't make the other association true. Those two associations of weekday and coffee in clues 3 and 5 are conditional on masking tape. I.e. IF masking tape is Tuesday, then Tuesday is associated with Harrar. IF masking tape is Wednesday, then Wednesday is associated with Sidamo. In this case masking tape is not associated with Wednesday, so we can't say if Wednesday is associated with Sidamo or not. The following table shows the count of new Xs (not dups) placed on successive passes through the entire list of clues as I solved the puzzle. Code:
Pass 1 Pass 2 Pass 3 Pass 4 Clue 1 7 0 2 1 Clue 2 2 5 0 0 Clue 3 1 5 0 0 Clue 4 3 0 0 0 Clue 5 1 4 2 1 Clue 6 4 0 0 0 Clue 7 1 0 0 0 Clue 8 2 6 3 1** You can see on the fourth pass, the newcomer Xs were starting to get scarce, but I still got three more. I usually don't make this many passes, but for this exercise, I didn't engage in any short cuts or combined passes. I just did a brute force (inefficient) top to bottom march through the logic. I was really curious to see how many passes it took on this difficult puzzle to finally get a positive. I spent more than 6 hours on this one the first time I saw it. I had diagrams and flowcharts, truth tables, and guess outcomes all over the place, and lots of wadded up paper in the basket. Keep at it. If you can solve this one, the others are going to look easy. 
#25




Hi my friend, I am pleased to hear that you too spent more than> 6 hrs on it your first time too! My brain is just about frazzled! I have a hard job keeping up with you Sir/Madam. Going through your chart I got lost when your 2nd pass got to clue 3 with 5 x's I didn't get any.I am up to your 5th clue with 4 x's I get zero. I am really tired it's late here. I will get back to you tomorrow. I really appreciate the help.
Stan 
#26




Hi Zenobia43, before you help me more can you show me where you get the 5 x's on your second pass on the second clue please? I only got 2. What am I missing? A lot most likely. BTW I would like to offer you the same sort of help in payment. I am an Astrologer and Horary Astrology is my speciality. Google it. I can answer any question you have. My email addy is stanley.sutherland@blueyonder.co.uk
I live in Edinburgh, Scotland. Stan 
#27




On the second pass, at first, it looks like clue 2 will only provide 2 additonal Xs.
Mateo cannot be Monday, and duct tape cannot be Tuesday. However, when these two Xs are placed, then duct tape can only be Wednesday or Thursday, and scotch tape can only be Thursday or Friday. Well then, one of those two tapes has to be Thursday, right? Clue 2 says duct and scotch tape must be one day apart, so that eliminates the possibility that duct tape is Wednesday when scotch tape is Friday. One of those two tapes must be Thursday to satisfy clue 2. That will make it impossible for the other three tapes to associate with Thursday. That is how you get 5 new Xs instead of just 2 on the second pass. On the second pass, clue 3 will provide 6 more Xs. In my table, I only show 5, so maybe that was a typo  or more likely, maybe I just missed one. On the first pass, clue 3 gave us Harrar cannot be Wednesday and Zoey cannot be masking tape. In the coffee/weekday category block, look at the intersection of Harrar and Wednesday. The Harrar column and Wednesday row make a cross. Notice that an X showed up in that cross after we placed the X from clue 3 at the intersection. Clue 4 gave us Wednesday cannot be Columbian. Clue 3 tells us that the only way Zoey and masking tape can be Columbian is if Columbian is Wednesday. This new X from clue 4 eliminated that possibility, so on pass 2, clue 3 causes us to add two new Xs: Columbian cannot be Zoey and Columbian cannot be masking tape. Now look at the cross formed by the Zoey column and masking tape row. There are two Xs from clue 1 in that cross (not counting the intersection), and we can use those two Xs to add 4 more Xs to the grid. Clue 3 tells us that the only way Erika or Lukas can be Wednesday or Harrar is if they are masking tape. The two Xs from clue 2 in the masking tape row eliminates that possibility, so we can add 4 new Xs. Erika cannot be Wednesday or Harrar, and Lukas cannot be Wednesday or Harrar. So either I screwed something up or we just got 6 more Xs. Continuing to clue 5 on the second pass, we look at the crosses formed by Tuesday and Sidamo, and Erika and masking tape. Nothing happened in the Tuesday/Sidamo cross, but we have two Xs from clue 1 in the Erika/masking tape cross that haven't been processed yet. Those two Xs in the Erika/masking tape cross will give us another 4 Xs. Two of the Xs will be in the Tuesday row (Lukas and Zoey), and the other two will be in the Sidamo row (Lukas and Zoey). You can probably see by now that the Xs from clue 1 (Zoey/masking tape cross and Erika/masking tape cross) could have be processed as we got to clues 3 and 5 on the first pass. After you do these puzzles a while, you instinctively focus on the clues that mention the same columns and rows. Last edited by zenobia43; 06172012 at 02:25 PM. 
#28




zenobia43 I understood what you explained up to here.
Continuing to clue 5 on the second pass, we look at the crosses formed by Tuesday and Sidamo, and Erika and masking tape. Nothing happened in the Tuesday/Sidamo cross, but we have two Xs from clue 1 in the Erika/masking tape cross that haven't been processed yet. Those two Xs in the Erika/masking tape cross will give us another 4 Xs. Two of the Xs will be in the Tuesday row (Lukas and Zoey), and the other two will be in the Sidamo row (Lukas and Zoey). You can probably see by now that the Xs from clue 1 (Zoey/masking tape cross and Erika/masking tape cross) could have be processed as we got to clues 3 and 5 on the first pass. After you do these puzzles a while, you instinctively focus on the clues that mention the same columns and rows. Can you explain how please? Stan 
#29




On the first pass, clue 5 only gave us one X: Sidamo cannot be Tuesday.
We could have gotten Erika cannot be masking tape from clue 5 as well, but that X was already obtained from clue 1. If we had wanted to be more efficient on the first pass, we would have noted that when we checked the intersection of Erika and masking tape, clue 1 already had provided 3 Xs in the cross formed by the Erika column and the masking tape row in the tape/first name category block. Clue 5 tells us that the only way Lukas or Zoey can be Sidamo or Tuesday is if they are masking tape. But looking in that cross, we see that clue 1 has already made it impossible for Lukas or Zoey to be masking tape, so that means that neither Tuesday nor Sidamo can be Lukas or Zoey. Therefore, on the second pass, clue 5 will give us 4 more Xs, or if we're efficient about it, clue 5 will give us 5 Xs on the first pass. I threw in this refinement partially to answer your question about how to know what to focus on. If you're not comfortable with this yet, don't fret. Just do the slow motion, brute force passes through the clues. Eventually you will have a pass that doesn't yield any more Xs, and you will know that either 1. The puzzle is almost solved, or 2. You misplaced an X or missed one, and most likely, you will have to start over or ask for help. By the way, a bit off topic, but I usually know I have to start over when I see a pattern of rectangles in the solution grid that are still missing Xs. If I see those rectangles, and I cannot extract any more logic out of the clues, then I probably placed an X in the wrong place. Sometimes the ordering clues will provide the solution, but a lot of the time, I just was off one cell (like when first names are almost identical) when I placed an X. And finally, a small suggestion  if we move on to a different puzzle after this one, personally, I would start another thread. This one got ridiculously long a long time ago Last edited by zenobia43; 06182012 at 12:17 PM. 
#30




Thank you very much Zenobia43 I managed after that.
Stan 
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