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In areas where such a tall fence is unsuitable (for example, on mountains subject to very high winds), deer may be excluded (or contained) by a fence of ordinary height (about 1.5 metres [4 feet 11 inches]), with a smaller one of about 1 metre (3 feet 3 inches) high, about 1 metre (3 feet 3 inches) away from it, on the same side as the deer.
Two manifolds of the same dimension are cobordant if their disjoint union is the boundary of a compact manifold one dimension higher. The boundary of an (+)-dimensional manifold is an -dimensional manifold that is closed, i.e., with empty boundary. In general, a closed manifold need not be a boundary: cobordism theory is the study of the ...
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. [1] A fence differs from a wall in not having a solid foundation along its whole length. [2] Alternatives to fencing include a ditch (sometimes filled with water, forming a moat).
Common heights include one-foot increments from 3 feet (0.91 m) to 8 feet (2.4 m), and other heights including 3 feet 6 inches (1.07 m), 10 feet (3.0 m), and 12 feet (3.7 m) although almost any height is possible. Mesh is commonly 9, 11, or 11 + 1 ⁄ 2 wire gauge. Mesh length can also vary based on need, with the standard diamond size being 2 ...
The signature of the intersection form is an important invariant. A 4-manifold bounds a 5-manifold if and only if it has zero signature. Van der Blij's lemma implies that a spin 4-manifold has signature a multiple of eight. In fact, Rokhlin's theorem implies that a smooth compact spin 4-manifold has signature a multiple of 16.
An electric fence is a barrier that uses electric shocks to deter people and other animals [note 1] from crossing a boundary. The voltage of the shock may have effects ranging from discomfort to death.
The purpose of perimeter fence is to stop or prevent the incident and reduce the level of risk. Doing so discourages the perpetrator from completing a harmful event. For example, a high wall with fence posts that protects a property discourages criminals from intruding and, when an incident occurs, increases the time it takes to carry it out.
In Canada spruce posts are sold for this purpose. Posts are 10 centimetres (4 in) in diameter driven at least 1.2 metres (4 ft) and may be anchored in a concrete base 51 centimetres (20 in) square and 110 centimetres (42 in) deep. Iron posts, if used, are a minimum 64 millimetres (2.5 in) in diameter. Bracing wire is typically smooth 9-gauge.