Revision cramming

Exams start tomorrow and finish two weeks later. I have so much random knowledge floating around my brain at the moment:

Computer System Design

Differential Manchester encoding is as normal Manchester encoding (with a regular transition in the middle of each bit-cell, used to regenerate the synchronising clock at the receiver end), except that 0 and 1 are indicated respectively by the presence and absence of a transition at the start of the cell.

Introduction to Software Engineering

Adding more people to a late project makes it later. Software myths #7: "By eliminating operators, human errors are eliminated." Software requirement specification should be: Correct, Nonambiguous, Complete, Consistent, Understandable, Modifiable, Traceable, Verifiable

Human-Computer Interaction

Soft Systems Methodology: Developed from the world of systems theory, this holistic approach seeks to understand the wider context in which the perceived usability problem lies. It identifies Clients, Actors, Transformations, Weltanschauung, Owners and the Environment in its analysis.

Logic For Computer Scientists

Binding priorities: The unary connectives (¬, AG, EG, AF, EF, AX and EX) bind most tightly. Next in the order come ∧ and ∨; and after that come →, AU and EU.

An occurence of x in Φ is free if it is a leaf node in the parse tree of Φ such that there is no path upwards from that node x to a node ∀x or ∃x. Otherwise, that occurrence of x is call bound. For ∀x ψ, or ∃x ψ, we say that ψ — minus any of its subformulas ∃x χ, or ∀x χ — is the scope of ∀x, respectively ∃x.

Automata and Formal Languages

Let G = ⟨V, Σ, S, P⟩ be a context-free grammar, and let ω ∈ Σ*. Then a derivation tree for ω in G is a labelled ordered tree satisfying the following: The root is labelled by S. Internal nodes are labelled by elements of V.singset. Leaves are labelled by elements of Σ ∪ {ε}. If A is a label of an internal node and X₁,…,X_n are labels of its children from left to right, then A → X₁,…,X_n is a production in P. Concatenating the leaves from left to right forms ω. We can show that ω ∈ L(G) if and only if there is a derivation tree for ω in G.

Systematic Software Design

The weakest precondition for the program P to establish the postcondition R, wp(P, R), is a predicate describing the set of all states from which execution of P is guarantees to establish R.

Data Structures and Algorithms

Since keys can be chosen to break any fixed hash function, the solution is to randomly choose a hash function from a carefully designed class of functions at the beginning of execution in a way that is independant of the keys that are going to be stored. Let H be a finite collection of hash functions that map a given universe, U, of keys into the range {0, 1, …, N-1}. H is universal if and only if for each pair of distinct keys k_i, k_j ∈ U, the number of hash functions h ∈ H for which h(k_i) = h(k_j) is at most |H|/N.

Knowledge-Based Systems

The General Boundary G with respect to a hypothesis space H and training data D, is the set of maximally general members of H consistent with D: G ≡ { g ∈ H | Consistent(g,D) ∧ (¬∃g' ∈ H)[g'>_gg] ∧ Consistent(g',D)

The Specific Boundary S with respect to a hypothesis space H and training data D, is the set of minimally general members of H consistent with D: S ≡ { s ∈ H | Consistent(s,D) ∧ (¬∃s'' ∈ H)[s>_gs'] ∧ Consistent(s',D)

Two nice things about tomorrow's exam (Introduction to Software Engineering) though: It's the least important exam (the module was 70% coursework), and through looking at the last five years of past papers, it appears that they set the same paper every year.

They've had exactly the same first two questions on the last two papers. There are a few questions that have been on four or five of the last five papers, and the rest of them crop up in about half the papers. And none of them are even good questions; they seem to mostly require us to have memorised certain acronyms, anecdotes or statistics related in the course notes rather than requiring us to, say, understand the course material, think about it and apply that knowledge to a question or situation.

Sigh. I realise I should be happy about having an easy exam, but I just find it very depressing how this module's been such a joke all the way through. And the icing on top? It's partly run by my favourite incompetent lecturer. Hopefully they'll be less-than-incompetent with the marking.

Wish me luck...

Brrm-brrm

Exams finished (thank goodness!) on Friday afternoon. Although most of them went rather well, better than my pessimism beforehand would have allowed, the stress levels around here have dropped dramatically in the last two days.

This means that at the moment, and for the next 3 months, I am free to do whatever I like! Unfortunately, as is so often the case in these situations, I suddenly have a strong urge to do absolutely nothing, and so all those lists I made of "things to do after exams have finished" are sitting around redundantly whilst I ignore them.

Despite my lethargy, I have managed to accomplish a couple of things this weekend. I have updated my books page wishlist in accordance with my Amazon wishlist, giving a total of 60 books I want to read but don't yet have. (I'm currently aiming to exhaust this list by the time I die. Maybe before then if I'm particularly industrious.) I have watched The Third Man (why oh why didn't anyone make me watch it before now?). And I have been learning to drive Kevin's car.

I do have rather a lot of experience driving different cars — two cars at home (and recently a third) plus a dozen or more rental cars whilst I was working during my gap year. I was quite happy with all of them; get in, adjust seat etc., and drive off with barely a stall during the whole year. I think my most traumatic experience was with the automatic-gearboxed car they mistakenly left for me once, with my panic that the car was going to stall every time I used the brake without touching the non-existent clutch. However, Kevin's car threw me for a loop.

We took it down to Sainsbury's carpark yesterday so that I could try driving around at low speeds, and I didn't do very well. My pulling away was rather abysmal, due to a) the accelerator being much more sensitive than I'm used to, and b) the clutch having a much higher biting point than I'm used to. This meant that every time I tried to pull away from a junction I would sit there with the revs getting ever louder and more embarassing until at last I would reach the biting point and we'd shoot off. (Kevin's car is also the first I've ever driven without power steering, which is taking some getting used to.)

I finished my "lesson" rather abruptly and Kevin drove us home since I was still too flustered to do so. However, we went back to Sainsbury's today (Sunday closing, carpark almost empty after 4pm) and I took on board what Kevin had said yesterday, and managed to drive rather well around the carpark. I even drove (2 miles) home afterwards. I think we might get on after all.