The Nest reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Nest

A nest is normally built by birds to hold their eggs and provide a home for their offspring. They are usually made of some organic material such as twigs, grass, and leaves.

Generally each species of bird has a distinctive style of nest. Nests can be found in many different habitats. Some birds will build them in trees, some (such as eagles, and many seabirds like kittiwakes) will build them on rocky ledges, and some will build them on the ground.

Common nest types:

• Ground nests
• Platform nests
• Cavity nests
• Cupped nests

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In functional analysis, a nest is a chain of subspaces of a vector space closed under intersection and union. The algebra of those operatorss leaving invariant every subspace in a nest is called the nest algebra associated with the nest. In particular, if the nest is finite, the corresponding nest algebra is just an algebra of block upper-triangular matrices.

See also

• flag manifold
• nest algebra
• operator algebra

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