The role of abstractions In this lecture, we are going to look at a very different style of creating large systems, a style called object oriented programming. This style focuses on breaking systems up in a different manner than those we have seen before To set the stage for this, we are first going to return to the notion of

luse this is the central part of the environment model, let's look in very painful detail at an example of an evaluation. In (square 4)I g particular, let's look at the evaluation of (square 4)with x;10 respect to the global environment. Here is the structure we start

Slide 12.1.1 In the last lecture, we introduced mutation as a component of 6001s|cP our data structures We saw for example that set was a Environment mode way of changing the value associated with a variable in our system, and we saw that set-car! and set-cdr! were ways of changing the values of parts of list structure Now, several important things happened when we introduced

ome of the theoretical exercise I will assign are actually well-known results; in other cases you may be able to find the answer in the literature. This is certainly the case for the current My position on this issue is that, basically, if you look up the answer somewhere it's your problem. After all, you can buy answer keys to most textbooks. The fact is, you will not

Beating the Averages Paul Graham (This article is based on a talk given at the Franz Developer in Cambridge, MA, on March 25, 2001 In the summer of 1995, my friend rt morris and i started a startup called Viaweb. Our pla to write software that would let end users build online stores. What was novel about this

Part I: Fill-In-The-Blanks(10\2=20 points is a collection of all accounts used by a business 2. All cash payments by check are recorded in the 3. Revenue and expense accounts are called because they are opened

16.61 Aerospace Dynamics Spring 2003 Lagrange's equations Joseph-Louis lagrange 1736-1813 http://www-groups.dcs.st-and.ac.uk/-history/mathematicians/lagranGe.html Born in Italy. later lived in berlin and paris Originally studied to be a lawyer

16.61 Aerospace Dynamics Spring 2003 Generalized forces revisited Derived Lagrange s equation from d'Alembert's equation ∑m(8x+16y+22)=∑(Fx+F+F。=) Define virtual displacements sx Substitute in and noting the independence of the 8q,, for each

Recall the following definitions: in any model M=(Q, (Ti, ai, piie), Ri is the event Player i is rational\;R=nieN Ri. Also, Bi(E) is the event \Player i is certain that E is true\ and B(E)=neN Bi(E). This is as in Lecture

Graphs(review) Definition. a directed graph(digraph G=(, E)is an ordered pair consisting of a set y of vertices(singular: vertex) a sete c× of edges. In an undirected graphG=(V, E), the edge set e consists of unordered pairs of vertices In either case, we have El=O(v2).Moreover if G is connected, then E2v-l, which