Fence

A fence is a structure that encloses an area, typically outdoors, and is usually constructed from posts that are connected by boards, wire, rails or netting. A fence differs from a wall in not having a solid foundation along its whole length.

Alternatives to fencing include a ditch (sometimes filled with water, forming a moat).

Types

By function

Fence (mathematics)

In mathematics, a fence, also called a zigzag poset, is a partially ordered set in which the order relations form a path with alternating orientations:

or

A fence may be finite, or it may be formed by an infinite alternating sequence extending in both directions. The incidence posets of path graphs form examples of fences.

A linear extension of a fence is called an alternating permutation; André's problem of counting the number of different linear extensions has been studied since the 19th century. The solutions to this counting problem, the so-called Euler zigzag numbers or up/down numbers, are

The number of antichains in a fence is a Fibonacci number; the distributive lattice with this many elements, generated from a fence via Birkhoff's representation theorem, has as its graph the Fibonacci cube.

A partially ordered set is series-parallel if and only if it does not have four elements forming a fence.

Several authors have also investigated the number of order-preserving maps from fences to themselves, or to fences of other sizes.

Horse jumping obstacles

Various obstacles are found in competitive sports involving horse jumping. These include show jumping, hunter, and the cross-country phase of the equestrian discipline of eventing. The size and type of obstacles vary depending on the course and the level of the horse and rider, but all horses must successfully negotiate these obstacles in order to complete a competition. Fences used in hunter and eventing are generally made to look relatively rustic and natural.

In jumping competition, they are often brightly colored and creatively designed. In hunter and jumper competition, obstacles are constructed to fall down if struck by the horse. In eventing, they are built to be solid, though for safety, certain elements may be designed to break away if hit.

Arrowhead

Also called chevrons, these fences are shaped like triangles, with the point facing towards the ground. They are generally very narrow, usually only a few feet wide. Arrowhead fences require the rider to keep their horse straight between their hands and legs, as it is easy for a run-out to occur due to the narrowness of the fence. These fences are often used in combination with other obstacles to increase their difficulty, such as right after a bank or as the second obstacle in a bending line. This tests the rider's ability to regain control of his/her horse following an obstacle.

Camping

Camping is an elective outdoor recreational activity. Generally held, participants leave developed areas to spend time outdoors in more natural ones in pursuit of activities providing them enjoyment. To be regarded as "camping" a minimum of one night is spent outdoors, distinguishing it from day-tripping, picnicking, and other similarly short-term recreational activities. Camping can be enjoyed through all four seasons.

Camping may involve sheltering in the open air, a tent, caravan, motorhome, or primitive structure. Luxury may be an element, as in early 20th century African safaris, but including accommodations in fully equipped fixed structures such as high-end sporting camps under the banner of "camping" blurs the line.

Camping as a recreational activity became popular among elites in the early 20th century. With time, it grew more democratic, and varied. Modern participants frequent publicly owned natural resources such as national and state parks, wilderness areas, and commercial campgrounds. Camping is a key part of many youth organizations around the world, such as Scouting, which use it to teach both self-reliance and teamwork.

Camping (1978 film)

Camping is a 1978 Dutch film directed bys Nolan Dow.

External links

Camping (game)

Camping, also known as campyon, campan, or campball was a Medieval football game played in England. It appears to have been popular in Norfolk and other parts of East Anglia. Of all the traditional forms of football played in Europe, it appears to have been one of the toughest and most dangerous. This probably explains why it died out during the early 19th century.

The first ever English-Latin dictionary, Promptorium parvulorum (ca. 1440), offers the following definition of camp ball: "Campan, or playar at foott balle, pediluson; campyon, or champion"

The game was originally played in the middle of town where the objective was to take the ball to the opposing side of town. It was later played in the country often in a special field set aside for the purpose known as a camping-place, camping close or camping pightle. A reminder of this old game can be found in Swaffham where, behind the market place lies the Camping land where the game was played. The custom in Medieval times was to play games after Church services and often camping fields were sited near the Church.