Opt-out

The term opt-out refers to several methods by which individuals can avoid receiving unsolicited product or service information. This ability is usually associated with direct marketing campaigns such as telemarketing, e-mail marketing, or direct mail. A list of those who have opted out is called a Robinson list.

In the UK, the Mailing Preference Service composes the Robinson list.

Telemarketing

The U.S. Federal Government created the National Do Not Call Registry to reduce the telemarketing calls consumers receive at home. Initially numbers listed on the registry were due to be kept for five years but will now remain on it permanently due to the Do-Not-Call Improvement Act of 2007, which became law in February 2008.

The UK's Direct Marketing Association operates an opt-out scheme through the Telephone Preference Service. While the service will reduce unsolicited calls it does not stop solicited calls, market research calls, silent calls or overseas calls.

Canada's National Do Not Call List operates an opt-out list which allows consumers to register their wishes not to have telemarketing calls. Charities, newspapers, and pollsters are exempt although each of these is required to keep their own do not call list that consumers can be added to at their request.

Opt-out (politics)

In politics, an opt-out is when one level of government can decline or refuse to be part of a program designed by another level of government.

Usage

The term is used in both Canada and the European Union, where it has roughly the same meaning. In both cases it refers to lower levels of government choosing not to participate in a program implemented by a higher level.

Canada

In Canadian usage opting out refers to a province's right to withdraw from federal programs. Debate often revolves aroung the question of compensation for provinces that choose to opt out.

European Union

Opt-outs in the European Union refer to areas of EU law that certain member states have not implemented.

Opt out (disambiguation)

Opt out is the term used in broadcasting when a nation or region splits from the main national output.

Opt out may refer to:

Opt

Opt or OPT may refer to:

Computing

Other

See also

Unix filesystem

In Unix and operating systems inspired by it, the file system is considered a central component of the operating system. It was also one of the first parts of the system to be designed and implemented by Ken Thompson in the first experimental version of Unix, dated 1969.

Like in other operating systems, the filesystem provides information storage and retrieval, as well as interprocess communication, in the sense that the many small programs that traditionally comprise a Unix system can store information in files so that other programs can read these, although pipes complemented it in this role starting with the Third Edition. Additionally, the filesystem provides access to other resources through so-called device files that are entry points to terminals, printers, and mice.

The rest of this article uses "Unix" as a generic name to refer to both the original Unix operating system as well as its many workalikes.

Principles

The filesystem appears as a single rooted tree of directories. Instead of addressing separate volumes such as disk partitions, removable media, and network shares as separate trees (as done in MS-DOS and Windows: each "drive" has a drive letter that denotes the root of its file system tree), such volumes can be "mounted" on a directory, causing the volume's file system tree to appear as that directory in the larger tree. The root of the entire tree is denoted /.

2-opt

In optimization, 2-opt is a simple local search algorithm first proposed by Croes in 1958 for solving the traveling salesman problem. The main idea behind it is to take a route that crosses over itself and reorder it so that it does not.

A complete 2-opt local search will compare every possible valid combination of the swapping mechanism. This technique can be applied to the travelling salesman problem as well as many related problems. These include the vehicle routing problem (VRP) as well as the capacitated VRP, which require minor modification of the algorithm.

This is the mechanism by which the 2-opt swap manipulates a given route:

Here is an example of the above with arbitrary input:

This is the complete 2-opt swap making use of the above mechanism:

Note: If you start/end at a particular node or depot, then you must remove this from the search as an eligible candidate for swapping, as reversing the order will cause an invalid path.

For example, with depot at A:

Swapping using node[0] and node[2] would yield