Imagine you’re in a queue to purchase food at a restaurant, for which pregnant women have priority. And there’s just a whole bunch of pregnant women arriving all the time. You’ll soon be starving. 😉 Now imagine you are a low-priority process and the pregnant women are higher priority ones. =)
That’s mostly a matter of tradition. It is not even always true. For example, floating-point units in processors (even contemporary ones) have 80-bits registers. And there’s nothing that would force us to have 8-bit bytes instead of 13-bit bytes. Sometimes this has mathematical reasoning. For example, if you decide to have an N bits byte … Read more
Let’s start with the Zipper-analog for lists. If you’d like to modify the nth element of a list, it takes O(n) because you have to copy the n-1 first elements. Instead, you can keep the list as a structure ((first n-1 elements reversed) nth element (remaining elements)). For example, the list (1 2 3 4 … Read more
The main advantage of a singleton over a class consisting of statics is that you can later easily decide that you need in fact more than one instance, e.g. one per thread. However, in practice the main purpose of singletons is to make people feel less bad about having global variables. A practical example for … Read more
Proofs are programs. Formal verification of programs is a huge research area. (See, for example, the group at Carnegie Mellon.) Many complex programs have been verified; for example, see this kernel written in Haskell (repaired 404 link is for seL4, see also the moved to location and the project’s website).
Moore’s UTexas webpage walks through both algorithms in a step-by-step fashion (he also provides various technical sources): Knuth-Morris-Pratt Boyer-Moore According to the man himself, The classic Boyer-Moore algorithm suffers from the phenomenon that it tends not to work so efficiently on small alphabets like DNA. The skip distance tends to stop growing with the pattern … Read more
I literally got assigned the halting problem, as in “write a monitor plugin to determine whether a host is permanently down”. Seriously? OK, so I’ll just give it a threshold. “No, because it might come back up afterward.” Much theoretical exposition ensued.
Paul Rendell implemented a Turing machine in Life. Gliders represent signals, and interactions between them are gates and logic that together can create larger components which implement the Turing machine. Basically, any automatic machinery that can implement AND, OR, and NOT can be combined together in complex enough ways to be Turing-complete. It’s not a … Read more
From Wikipedia: A description of a function in terms of big O notation usually only provides an upper bound on the growth rate of the function. From this description, since the empty algorithm requires 0 time to execute, it has an upper bound performance of O(0). This means, it’s also O(1), which happens to be … Read more
You’re correct that it cannot guarantee uniqueness, however there are approximately 3.402823669209387e+38 different values in a 32 digit hex value (16^32). That means that, assuming the math behind the algorithm gives a good distribution, your odds are phenomenally small that there will be a duplicate. You do have to keep in mind that it IS … Read more