Mathematical construct, the extension of a predicate, that is, all things with a given property. Given a predicate A(x), we can write { x | A(x)} to mean "The class of all x such that A(x) is true."

An object is an element of a class if it satisfies the predicate that defines it. Classes may not be considered as elements of classes or sets; only sets may be. If a given set has the same elements as a given class, then the set is said to represent the class; a large portion of set theory is dedicated to determining which classes are represented by sets.

Some examples of classes include:

In the early 1900s, several paradoxes arose which cast the validity of set theory into question. The most famous of these is Russell's Paradox, which occurs if you allow the class of all sets which do not contain themselves as elements to be represented by a set. The class of all sets cannot be represented by a set, otherwise the class that results in Russell's paradox would have to be. In general, if {x|A(x)} is represented by a set, then {x|~A(x)} cannot be, otherwise, the union of those two sets would be a set representing the class of all sets. Of course, this does not exhaust the classes that are not represented by sets!

Bertrand Russell and Alfred North Whitehead, in their Principia Mathematica, introduced a system known as type theory which avoided these paradoxes. However this system was unsatisfyingly complex. And so type theory was eventually simplified into the distinction between classes and sets.

I'm three quarters of the way through my take-home final exam for Linguistics 305: Syntax (Introduction to Government and Binding in Generative Grammar). That is to say -- I've worked for six hours, and expect to work another six.

In four years of undergraduate education, I have never before been asked to or needed to apply such mental energy to schoolwork as this final exam is asking me to.

And that's the point of it, according to Professor Ken Safir. I've never had a better professor. He doesn't just teach, he explains. He builds up paradigms of thought bit by bit until everyone in the class is bouncing in their seats with expectation because they've all figured out on their own what's coming next. He makes things make sense. And he doesn't assign busywork. Even the final exam is intended to teach us something -- he informed us outright that much of the material on the final was never discussed in class -- "but some deep thinking should allow you to synthesize what you need for the solution."

Why can't all classes be like this? It bothers me that universities don't draw distinctions between "hard" and "easy" classes.

I'm expecting to earn a B+ in this class -- and I do mean earn. I've struggled with the material, and overcome it, and burned new and useful pathways into my cognitive machinery. I learned in this class. Time and again, poring over the week's material until finally a light went on and I Understood.

On the other hand, I'm expecting to receive an A in Social Psychology. I went to class twice the entire semester. The tests are open-notes, multiple-choice. It's a 300-level, 3-credit class, just like Syntax. My "academic standing", whatever that is, will be raised more by Social Psych -- a class I didn't attend and received no benefit from -- than by Syntax, a class that caused me to do more deep thinking than any other I've ever taken.

There must be a better way.

In c++, a class is a formalized definition of data and methods from which an object can be instantiated.

Class members are divided into three groups: public, private, and protected.

For example:

class A
{
public:

int GetValue();
int SetValue();

private:

int nValue;

};

Socially speaking, a class is different from a caste in that an individual's class may change throughout their life or from one generation to the next.

Most Western countries have a class system, to one degree or another. If your parents are poor you will probably be poor too, but you might improve your situation through hard work or luck. Likewise, you might be better able to provide for your children.

In a caste system, the social group you are born into is the caste you will die in, period. I believe India still has a caste system, which is closely tied to their religion. They believe that if you do well in life, then in the next life, you may be reincarnated into a more prestigious caste. This belief helps provide stability to a social system that would otherwise be weakened by the great number of people in low castes who are helpless to do anything about it within their culture.

The acronym for Custom Local Area Signalling Service. This is the SS7 service that allows automatic call return (*69) and repeat dialing (*66). For *69 the person recieving the call does not answer. The recipiant then picks up the phone and dials *69. The SSP serving them initiates a query on the last number to call the line to an SCP. The SCP does a lookup to find out where the calling number resides and launches a query to the SCP responsible for that area. This SCP then determines the end SSP and notifies it of the request to initiate a call to the originating number. The SSP then sends a response to the SSP that originated the CLASS query and a normal ISUP call is started.

In the Three Domain taxonomy of life, Class is the fourth of the eight ranks:
1. Domain
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species
For Homo Sapiens (us), the class is Mammalia:
Eucarya.Animalia.Chordata.Mammalia.Primates.Hominidae.Homo.sapiens

A 1983 book by essayist, historian, sociologist, and literary critic Paul Fussell which attempts to detail and analyze the structure of the American status system. It became a personal favorite years ago, and still greatly influences the way I perceive fellow Americans.

Fussell's cruelty is somewhat mitigated by its equality: he has unabashed disdain for all classes. Though we, as readers, may wince when we find our values, beliefs, and cultural artifacts singled out for ridicule, there is a comfort in the knowledge that his analyses will soon pass to less sensitive targets (i.e. our neighbors).

The American status system is divided into nine classes:

Top out-of-sight
Upper
Upper Middle
------------
Middle
High proletarian
Mid-proletarian
Low proletarian
------------
Destitute
Bottom out-of-sight

Fussell goes to great lengths to clarify that it is not riches alone that define class, but rather a combination of wealth, style, taste, awareness, manners and traditions which generally persist from birth to death. There is a tendency for class drift, but fundamental markers of class designation are unlikely to change even through radical changes in income. For it isn't that the three classes at the top don't have money. Rather, money alone doesn't define them, for the way that they have their money is largely what matters.

The name of the "top out-of-sight" class comes from an interview with a Boston blue-collar worker, who when asked about wealth said, "When I think of a really rich man, I think of one of those estates where you can't see the house from the road." For Fussell, the top class could just as well be called the "class in hiding." Their houses are never seen from the street or road. They like to hide away deep in the hills or way off on Greek or Caribbean islands (which they tend to own), safe, for the moment, from envy and its ultimate attendants, confiscatory taxation and finally expropriation. They tend to be removed from scrutiny, escaping the down-to-earth calculations of sociologists, poll-takers, and consumer researchers. It's not commonly studied because it's literally out of sight.

The next class down, the upper class, differs from the top-out-of-sights in two main ways. First, although it inherits a good bit of money, it earns quite a bit too, typically from some attractive (if slight) work without which it would feel bored or vaguely ashamed. They tend to make money owning banks, controlling think tanks or foundations, running the more historic corporations, and busying themselves with things such as universities, the Committee for Economic Development, or the Executive branch of the government. But more importantly, the upper class is visible, often ostentatiously so. Fussell claims that while the out-of-sights have spun away from Veblen's theory of conspicuous consumption, the mere upper class have been left to carry on instead. When you pass a house with an impressive facade visible from the street, you know it is occupied by a member of the upper class.

While Fussell's cruelty may be equally distributed, it seems at times that he reserves an especially acute edge for the middle class. The middle class is distinguishable by its earnestness and psychic insecurity rather than by its middle income. Rich people who remain terrified at what others think of them, who are obsessed with doing everything right so as to avoid criticism, are stubbornly middle class. The middle class is the place where table manners assume an awful importance and mouthwashes and deodorants abound. The middle class is ascribed a certain "status panic" and continually looks to borrow status from higher elements. There is no latitude for individuality and eccentricity; you are nothing if not "part of the team.".

The middles lust for the illusion of weight and consequence, seeking heraldic validation ("This beautiful embossed certificate will show your family tree") and issuing annual family newsletters announcing the more recent triumphs in the race to become "professional". Nervous lest she be considered nobody, the middle-class wife is careful to dress way up when she goes shopping. Correctness and doing the right thing become obsessions, prompting thank-you notes for the most ordinary dinner parties. The desire to belong overwhelms. The middle-class man, according to Fussell, is scared. He is always somebody's man, be it the corporation's, the government's, or the army's.

The young men of the middle class are, in Fussell's words, "chips off the old block." You can see them on airplanes, being forwarded from one corporate training program to another. They consume John T. Molloy's books, hoping to break into the upper-middle class by formulas and mechanisms. Their talk is of the bottom line, and for no they are likely to say no way.

The disappearance of the lower-middle class is an area of concern for Fussell, one that forced him to delete that class entirely, and replace it with varying degrees of proletariat. The inflation of the 60's and 70's and the social demolition that resulted pauperized the true lower middle class, a class whose solid high-school education and addiction to saving and planning maintained it in a position above the pure working class. The former low white-collar people are now simply working machines, and the wife usually works as well as the husband.

The kind of work and the sort of anxiety that besets one as a result provide the main delineations of the proletariat for Fussell. The high proles are the skilled workers and craftsmen, such as printers. The mid-proles are the operators - think Ralph Cramden, the bus drivers. The low proles are unskilled labor, like longshoremen. The special anxiety of the high proles is fear about loss or reduction of status: you're proud to be a Master Carpenter, and you want the world to know the difference between you and a laborer. The special anxiety of the mid-proles is fear of losing the job. And of the low proles, the "gnawing perception that you're probably never going to make enough or earn enough freedom to have and do the things you want."

Follow the nodes for specific information on the class implications of personal appearance, your house, consumption, recreation, speech, and the X Class.
In Object Oriented Programming, a class is a name for the basic unit of code, also called a module. Objects can be instantiated from a class, and the class definition provides "rules" of how that object will behave at runtime, and what can be done to it.

Encapsulation is key to the idea of classes, and OOP. Ideally, classes should be a representation of some object in the real world that we can directly relate to - for instance, a Rectangle class should be able to define its position, size - everything about it we would expect to know in the real world - and allow us to manipulate it as we would in the real world.

Classes contain two main things to allow them to do this: data members and member functions. The data members are the bits of memory that store the information a class needs to do its job, and the member functions are the actual operations that provide the functionality of the class.

Objects communicate with each other by calling each other's member functions (also known as "sending a message" to that object). It is considered very bad form to direct manipulate another objects' data members, so classes should provide what are commonly known as "Get/Set" functions (because, say, for a data member called Size, they will usually be called GetSize() and SetSize()) to manipulate the data. This is very important for one main reason: consistency of state.

If an object is allowed to directly manipulate another object's data members, then its member functions essentially "lose track" of these data members. Imagine a Rectangle class that only allows itself to be 200 pixels wide. If another object sets its width to 250 pixels, it is likely the class will start to behave incorrectly. The whole idea of OOP is that an object gets to decide for itself how things are done, and that every other class in the system doesn't really need to know how these things are done. If objects are going to start messing around with each other's internal data, this whole system falls down.

Now for a little programmerese (as if the above wasn't enough!) Classes, in general, can either exist in solution space or implementation space. Remember how I said a class represents some concept in the real world? That's a class in solution space - it represents an object that exists as part of our solution, such as letters, words and fonts in a word processor. These types of classes are often referred to as abstract types (but this is also a more general term, so don't get too wrapped up with it).

Classes in implementation space are classes representing objects that exist in the implementation of a program and have a relevence to it, but aren't immediately obvious as part of the solution. These are often concrete types. As an example, in implementing a word processor, I might use a linked list or a deque to store sentences, but this isn't immediately obvious from problem. Linked lists are needed to implement the program, but they cannot be directly mapped to an object or concept in the problem.

One of the main tasks of Object Oriented Design is what's called "Finding the classes", which is to say, deciding what classes should be used in a system to represent and build the solution.

Also, a state of grace, stylishness, or cool; possessing je ne sais quoi. Slang, probably derivative of a desire to emulate the higher ranks in society; classy;

With respect to the zephyr messaging system, a class functions as a cross between a BBS and a chatroom. Each zephyr has a class and an instance. Standard personal zephers are class "message", instance "personal", but a user can send a message to any class or instance.

To get messages sent to a class, a user subscribes to that class. Users may subscribe to all instances of a class by using a wildcard, or to specific instances. Users may not, however, use a wildcard to subscribe to all classes. This allows the existence of private zephyr classes, with unpublished names.

Certain zephyr classes and instances are well-known and high traffic, such as MIT's class help. On many such public classes, it is conventional and good manners to use the instance of your zephyr to denote your topic, to enable many parallel conversations.

There is a strong case to be made for the idea that almost all of the world's biggest problems are caused by rich, white male wankers. Relatedly, it can be argued that almost all of the world's major struggles are part of one big fight against the same privileged, self-regarding class of people who run almost everything - although this risks ignoring the differences in the changes that people hope to achieve.

Class has always been a big thing in Britain, as in much of the world, to the extent that the Conservative Prime Minister John Major's talk of creating a 'classless society' was met with widespread ridicule, and we tend to have a similar response when people suggest that such a society exists in the USA. It is currently fashionable in this country to openly deride 'chavs' (or 'neds' in Scotland) - which is shorthand for 'working class, possibly unemployed people who scare and/or revolt me' - and it has never gone out of fashion to pour scorn on anyone perceived as upper class.

Among other things, social class is a very convenient way to dismiss someone, without having to engage with what they're saying. This is not always unreasonable - it is difficult for those born into positions of privilege to understand the problems faced by those who aren't. Perhaps there is some truth in the reverse, too. On the other hand, all of these things are relative, and almost all of us do face many of the same problems, whether we face up to them or not.

Maybe two thirds of Britons these days think of themselves as being middle class (depending on which surveys you believe) but on a Marxian analysis, the proletariat is just as large as ever. The control of the means of production is still overwhelmingly in the hands of a very small number of people. Almost everyone still needs to work hard for a living, and much of what we make still goes to the benefit of the very rich.

Social class remains important, but economic oppression is bigger than that. Our economic system is not run chiefly for the benefit of the 'middle class', whatever that might mean. It is run for the benefit of capitalists - people with the money to make money - and their power is greater, but more fragile, than ever. The extremely rich look on and chuckle when we devote more of our energy to tearing each other apart than we do to tearing down the structures that allow them to maintain their stranglehold.

Class (?), n. [F. classe, fr. L. classis class, collection, fleet; akin to Gr. a calling, to call, E. claim, haul.]

1.

A group of individuals ranked together as possessing common characteristics; as, the different classes of society; the educated class; the lower classes.

2.

A number of students in a school or college, of the same standing, or pursuing the same studies.

3.

A comprehensive division of animate or inanimate objects, grouped together on account of their common characteristics, in any classification in natural science, and subdivided into orders, families, tribes, gemera, etc.

4.

A set; a kind or description, species or variety.

She had lost one class energies. Macaulay.

5. Methodist Church

One of the sections into which a church or congregation is divided, and which is under the supervision of a class leader.

Class of a curve Math., the kind of a curve as expressed by the number of tangents that can be drawn from any point to the curve. A circle is of the second class. -- Class meeting Methodist Church, a meeting of a class under the charge of a class leader, for counsel and relegious instruction.

Class (?), v. t. [imp. & p. p. Classed (?); p. pr. & vb. n. Classing.] [Cf. F. classer. See Class, n.]

1.

To arrange in classes; to classify or refer to some class; as, to class words or passages.

⇒ In scientific arrangement, to classify is used instead of to class.

Dana.

2.

To divide into classes, as students; to form into, or place in, a class or classes.

Class, v. i.

To grouped or classed.

The genus or famiky under which it classes. Tatham.