Echo's sister, Kik, woke me up this morning to ask about diagrams. Early cat catches the mouse, sort of thing. "Mmph Meowrf MEOWFFM Pbbbtt" "Kik, what's in your mouth?" "A pweffent." "What the hell do you have in your mouth? Spit that out." A moment later... "A present! I brought you a present. It's a mouse. Now help me." "That's not a mouse. It's a computer mouse. MY computer mouse, I might add." "Whatever. Same thing. Help me." "Help you with what?" "Diagrams. Echo said you helped him, so I need you to help me. I think I get it, but I need you to take a look. I worked that problem about the scientists, and here's my diagram." "Oh, you mean Logic Game #1, questions 15 from Test 42, Section 1" I said for totally unnecessary reasons having nothing to do with copyright or why I can't show you the specific problem without getting sued. "Yea, nailed it. Good for you. Look..." "Yeah, I see your problem" I said. "But I followed your advice about diagrams! If there's a problem, that's on you." "Well, you did and you didn't. Let me explain..." The test allows approximately 8m45s per logic game. That's not a great deal of time, and so every second counts. Your diagram should use the least amount of effort, and take the least amount of time as possible. So never write out things like Botanist, Chemist, Zoologist. Use abbreviations or better yet, just use the letter with a circle around it. The circle tells you it's a category, not a variable. I do like that you organized the variables by category. Very good thinking. But then you have "5" and "1 of each." That's too confusing. There's a simpler way to represent that only 5 variables are selected and at least one from each category. (See diagram below) But I really don't like how you diagrammed your rules. "Why not?" Kik asked, "They're logically sound representations of the rules, aren't they?" "Yes, they are. And they express exactly what the rule states, which is great. But they're not really usable at a glance. I'm going to have to do work to "convert" these rules into something that allows me to draw inferences and apply those rules to questions. And I'm lazy, like you ("Hey!"), and I don't want to do work  also like you (<shrug>). Taking a little extra time to represent the rules in a logically usable and visually obvious way will save time later on. Here, look at my diagram. "I don't get it," said Kik. "What's so great about this diagram compared to mine?"
Well let's start with speed. I didn't spend time writing out the categories. Circled letters, easy and fast. I didn't write out "1 of each" I just put dashes next to each category. Then I added two out to the side, as well. This tells me that there is one of each category, + 2 from any category. Not only that, but I represented those conditions in a visually obvious way. It's immediately clear how many variables are needed and of what type. Now look at my rules. See, the LSAT wants to confuse you by stating the first rule in terms of Botanists and Zoologists. If you write B and Z, then you have to go back to your variables, look at who is what, then translate the rule. I skipped all of that extra work and just wrote the rule in terms of the variables themselves. After all, it's the impact on the variables that matters for answering the questions. So, my rule says "2 or more of FGH, then 1 of PQR." Yeah, I know the rule states "at most one of PQR" but that's just the LSAT trying to trick me. "At most one" logically means 0 or 1. But it CAN'T mean 0, can it? There must be one of each category, so "at most" 1 means just...one. "But why," asked Kik "did you represent F x K vertically and K x M horizontally?" Because that's how I structured my variables. See, F and K apply to different categories. And I stacked my categories. So, I stack that rule. Why? Because it visually matches how I've organized the problem, and so it is visually easier to reference. And I want it to be as easy and obvious as possible. But K and M are from the same category, so I diagram that rule horizontally. Now, the "If M, then P + R" rule" is a conditional. But why express it as a conditional in logical form? Why not express it as it appears visually in the problem? So I use the curvy F symbol to indicate "If M." (that's my shorthand, and it works for me. use whatever you can draw with your kitty paws). It's important that this rule hinges on M being selected, and I want to represent that. But then I draw it stacked with PR beneath. Why? Because that's how I've organized my problem! At a glance, I can see the conditional. I've done the same with the two inferences at the bottom. There are more inferences, but I just want you to see how I diagrammed them. I diagrammed them to be visually obvious based on my organization of the problem. I don't have to piece the inference together. It's visually available. "You see?" "Yeah," said Kik "but I'm tired. I saw you ironing earlier. I think I'll go nap on your clothes."
0 Comments
Leave a Reply. 
AuthorFree stuff related to the LSAT. This blog includes reflections, tips, strategies, and problem solving for the LSAT. Feel free to email questions. I'll be happy to answer them on my blog. ArchivesCategories
All
