It all seems fine when I learn the logical symbols separately, but when it comes down to actually using it to express a statement, I can't figure out where to start. For example, when I first looked at this weeks tutorial handout, I gave up after looking at the first question thinking in my head that I'll learn it in class and that would be enough to cope for the quiz. Although I gave up at that moment, I still went back to try it again another time. After hours of reading and asking friends, trying to figure out where to start, I finally came up with some answers that seemed right at the time (they were). The problem was knowing when to use the "," and the order of the symbols. At first I thought order didn't matter for declaring which variable is in which set and the quantification of it, but in the tutorial today I learned that order does matter and it's a serious mistake to have the wrong order. The whole statement changes. As soon as the questions started to get harder I was back to the start, where the only thing left to do was to quit! My problem was that I didn't know how to put the symbols together, plain and simply. I'm not quite sure if I was suppose to know this notation before taking this course. Either way, I'm going to practice trying to express harder claims in symbols to try and get the hang of it, and if anyone knows any practice questions with solutions available anywhere, please let me know as this will help me greatly.
The "," is only used for separating variable declarations, just that. That's why when you have two predicates, you don't put a comma between them. Predicates return True/False values and so you want to know how they relate to each other, and thus you should use AND, OR, etc.
ReplyDeleteConcerning the more difficult examples from the tutorial, you need some time to understand them. Read the solution many times and make sure you understand it. So, don't quit! It's the first time you come across this stuff! In the next couple of weeks it will be a piece of cake for you.