This week we learnt some useful symbols and ways of expressions for CSC165. I have known that "unless" can be translated into "if not".And I can finally tell the difference between the symbol of conjunction and symbol of implication and how to use them under different circumstances. Conjunction is referred to "and" in English and disjunction is referred to "or".I also learnt negation. If a statement is true, then its negation must be false. The symbol of universal quantification and existence quantification can be changed into each other by the way of negation, which is a convenient method.In addition, I learnt that drawing venn diagram is not the only way to translate an expression. We can also use tabulating truth by drawing a table with T and F, which is more easily to understand. Moreover,tautology means the statement is true in every possible world. We call a statement satisfiable if it is sometimes true while we call it unsatisfiable if it is never true. There is an interesting law called De Morgan's Law which switch the roles of the symbol of conjunction and disjunction as with magic.In the last class this week, we played a game by folding a strip for several times. Firstly, I found it very difficult cause I have no idea. After several minutes of thinking I figured out how to get started.During that progress, I found the regular pattern gradually and can predict the sequence of ups and downs. It is so funny.
Next week we will have the first CSC165 test. I wish I can do it well.
Monday, January 28, 2013
Saturday, January 19, 2013
SLOG for CSC165 week2
It is the second week of this semester and I learnt a lot of new things in CSC165.
I become more familiar with existential claims than the last week. And I am more skilled at evaluating quantified claims now. We learnt the universal and existential duality,which need us to draw Venn graphs with X and O and ?.I did a good job on this part ,which makes me confident.It is important to tell a sentence from a statement. All the statements are sentences but not all the sentences are statements. We can use quantifying to change an open sentence into a statement,which can be evaluated to true or false. I found it interesting that existential statement is not only about the interset of two sets are empty but also about one set is not a subset of the other one's counterset.We also learnt implication with the form of "if A,then B". A is the antecedent while B is the consequent. I also learnt a concept called contrapositive. Which occurs when we toggle and reverse an implication. For this part , it is a little complicated. Vacuous truth is also a little triky. It is always true except when antecedent is true and the consequent is false. It is hard to understand because it is different from the true in daily life. It works because there are no counterexamples. Then we are taught about different expressions of equivalence.
I have gained a lot of knowledge this week and I would work hard to remember all of these things. See you next week!
I become more familiar with existential claims than the last week. And I am more skilled at evaluating quantified claims now. We learnt the universal and existential duality,which need us to draw Venn graphs with X and O and ?.I did a good job on this part ,which makes me confident.It is important to tell a sentence from a statement. All the statements are sentences but not all the sentences are statements. We can use quantifying to change an open sentence into a statement,which can be evaluated to true or false. I found it interesting that existential statement is not only about the interset of two sets are empty but also about one set is not a subset of the other one's counterset.We also learnt implication with the form of "if A,then B". A is the antecedent while B is the consequent. I also learnt a concept called contrapositive. Which occurs when we toggle and reverse an implication. For this part , it is a little complicated. Vacuous truth is also a little triky. It is always true except when antecedent is true and the consequent is false. It is hard to understand because it is different from the true in daily life. It works because there are no counterexamples. Then we are taught about different expressions of equivalence.
I have gained a lot of knowledge this week and I would work hard to remember all of these things. See you next week!
Monday, January 14, 2013
SLOG for CSC165 1
It is the first week I attend CSC165. I am excited to explore this new field of knowledge.This course is about mathematical expression and reasoning for computer scientists.
There are a lot of interesting topics such as logic and expression,proof technique...This week I learnt that precision is very important for computer science by distinguishing the differences between 4 functions which look similar but with different meanings regarding 'every' and 'some'.Even though the 4 functions are hard to distinguish at first, I finally managed to figure them out! And I finally can tell the difference between lists and sets,which makes me very happy.We also learnt quantifiers by the example of employees. The symbols about exists and all and other interesting ones are new things to me and I found them very useful in expressing an equation. The knowledge about universal quantification and existential quantification is challenging and I really enjoyed the progress of learning them.
CSC165 is a challenging and interesting course and I have the confidence to conquer it so that I will do well in the CS major.
There are a lot of interesting topics such as logic and expression,proof technique...This week I learnt that precision is very important for computer science by distinguishing the differences between 4 functions which look similar but with different meanings regarding 'every' and 'some'.Even though the 4 functions are hard to distinguish at first, I finally managed to figure them out! And I finally can tell the difference between lists and sets,which makes me very happy.We also learnt quantifiers by the example of employees. The symbols about exists and all and other interesting ones are new things to me and I found them very useful in expressing an equation. The knowledge about universal quantification and existential quantification is challenging and I really enjoyed the progress of learning them.
CSC165 is a challenging and interesting course and I have the confidence to conquer it so that I will do well in the CS major.
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