week 9 - Formal Languages

For week 9, we had a term test. I was initially quite worried about the test. Had to revise the material over and over again before the test. It doesn't help if i have to work on Thursdays before lecture. But luckily i had time to go through the material one last time before the test. It turned out that the test was ok. The last question did not work out too well but it was ok. I think i forgot to read the last question properly. But it's work 2 marks so hopefully it will not hurt the overall score too much.

During lecture, we did formal languages. So a set of strings is a language. Strings consist of symbols from an Alphabet. Then a language consists of a set of all possible string over the alphabet. So a language is a subset of the alphabet?

Again, nothing made sense during lecture. Had to re-read the slides after i got home. Something confused me a little. For the equality of languages, the example we did was to prove that L1 = {x has an even number of zeros} and L1 = (1*(01*01)*). For Xi, why is the substring starting at (2i-1)and ends at the (2i+1)th 0? Why 2i? Shall ask Danny when during office hours then.