By far the best professor i have seen that explained theory of computation! Thank you for your great efforts you helped me ace the material for my test !
Of all the Theory of Computation videos on youtube, this series is the best. But in this video in particular, there is a serious error. The diagram he points to at 29min 13sec is very misleading. The previous diagram had self transitions on these states. Where did they go? The diagram also misrepresents the situation when i = j when it would look very different. The statements he makes at 28min 46sec and 30min 3sec are incorrect. Not only the red edges matter. Strictly speaking, the transition from i to j is replaced by the transition from i to i then i to j then j to j. Leaving this subtlety out just saves writing and later simplifying except for the case when i = j when it will result in an incorrect regular expression. Like he correctly states, all edges must be modified. At 30min 58sec he reiterates this by mentioning literally every edge in the graph that must be modified but leaves out the self transition edges! This method will not in general produce the correct regular expression unless the self transitions are modified. The path i to i can also be made i to i (R5), i to rip (R1), rip to rip (R2), rip to i (R6), i to i (R5). So R5 must be replaced by (R5)*(R1)(R2)*(R6)(R5)*.
![[3b-2] Minimal states and equivalence classes (COMP2270 2017)](/img/n.gif)
People like you needs to live long.
He is really good. Perfect mix of formalism and examples
By far the best professor i have seen that explained theory of computation! Thank you for your great efforts you helped me ace the material for my test !
love the way you use small steps to build up the whole thing
Prof. Harry, you're awesome. Thanks for sharing your knowledge!
I believe there is a mistake at 33:34. The c state is missing a transition for the letter 2, so the machine is a NFA rather than a DFA.
This is a work of art!
Sir, you have taken a course that I’ve started to absolutely despise with a passion, and make it interesting
Thank you so much!
This one was long but everything was clear. It did not seem like 40 minutes at all. Thanks.
You are a Saviour !!
Can a DFA have multiple symbols over a single transition??? 20:59
yes
i love this man
Of all the Theory of Computation videos on youtube, this series is the best. But in this video in particular, there is a serious error.
The diagram he points to at 29min 13sec is very misleading. The previous diagram had self transitions on these states. Where did they go? The diagram also misrepresents the situation when i = j when it would look very different.
The statements he makes at 28min 46sec and 30min 3sec are incorrect. Not only the red edges matter. Strictly speaking, the transition from i to j is replaced by the transition from i to i then i to j then j to j. Leaving this subtlety out just saves writing and later simplifying except for the case when i = j when it will result in an incorrect regular expression.
Like he correctly states, all edges must be modified. At 30min 58sec he reiterates this by mentioning literally every edge in the graph that must be modified but leaves out the self transition edges! This method will not in general produce the correct regular expression unless the self transitions are modified.
The path i to i can also be made i to i (R5), i to rip (R1), rip to rip (R2), rip to i (R6), i to i (R5). So R5 must be replaced by (R5)*(R1)(R2)*(R6)(R5)*.
Thanks for this explanation, can you point to any examples when i=j. I was under the illusion that each state would be distinct.
Prof. Harry Potter
Professor Harry Potter