EDIT (much later than original answer): MarkCC of Good Math, Bad Math recently wrote up an excellent discussion of the Halting problem with concrete examples. The halting problem is basically a formal way of asking if you can tell whether or not an arbitrary program will eventually halt. In other words, can you write a … Read more
The Internet itself pre-dates 1980, but the World Wide Web (“distributed hypertext via simple mechanisms”) as proposed and implemented by Tim Berners-Lee started in 1989/90. While the idea of hypertext had existed before (Nelson’s Xanadu had tried to implement a distributed scheme), the WWW was a new approach for implementing a distributed hypertext system. Berners-Lee … Read more
Generally it means that by increasing the level of abstraction one can make the problem easier to understand/resolve. Be careful with your abstractions though, the full quote at least as I heard it is, “You can solve every problem with another level of indirection, except for the problem of too many levels of indirection”.
I assume that you are looking for intuitive definitions, since the technical definitions require quite some time to understand. First of all, let’s remember a preliminary needed concept to understand those definitions. Decision problem: A problem with a yes or no answer. Now, let us define those complexity classes. P P is a complexity class … Read more
The value is in the brackets. The registers in the brackets should be represented by their values too.
I think you can just have an id that automatically increments and make it your primary id. Then, your checking should be to check the student number and syearid and status before allowing the student to vote. with that you can just have 1 table for the vote records.