Ecological Sustainability

439Glossary

rank A ≤ min(n, m). For an n × n matrix A, a necessary and sufcient

condition for rank A = n is that |A| ≠ 0 (Ogata 1987).

recession (in economics): A contraction phase of the business cycle. A reces-

sion is said to occur when the real GDP is negative for two or more

consecutive quarters. Recessions may include bankruptcies, dea-

tion, foreclosures, unemployment, reduced sales, and stock market

crashes.

redox reactions: Chemical, reduction–oxidation reactions. An oxidized

chemical loses electrons; a reduced reactant gains electrons. An oxi-

dizer gains electrons, that is, is reduced.

Red Queen Contest (in ecological genomics): It occurs when two, compet-

ing, complex biological systems interact, for example, a quasi-species