problem of reduction
121Recursion theory — Recursion theory, also called computability theory, is a branch of mathematical logic that originated in the 1930s with the study of computable functions and Turing degrees. The field has grown to include the study of generalized computability… …
122Union of Soviet Socialist Republics — a former federal union of 15 constituent republics, in E Europe and W and N Asia, comprising the larger part of the former Russian Empire: dissolved in December 1991. 8,650,069 sq. mi. (22,402,200 sq. km). Cap.: Moscow. Also called Russia, Soviet …
123Military Affairs — ▪ 2009 Introduction Russia and Georgia fought a short, intense war in 2008, fueling global fears of a new Cold War. On August 7 Georgia launched an aerial bombardment and ground attacks against its breakaway province of South Ossetia.… …
124Social Protection — ▪ 2006 Introduction With medical costs skyrocketing and government programs scaled back, citizens bore more responsibility for their health care costs; irregular migration, human trafficking, and migrant smuggling posed challenges for… …
125NP-hard — For a gentler introduction, see P versus NP problem. Euler diagram for P, NP, NP complete, and NP hard set of problems NP hard (non deterministic polynomial time hard), in computational complexity theory, is a class of problems that are,… …
126P-complete — In complexity theory, the notion of P complete decision problems is useful in the analysis of both: which problems are difficult to parallelize effectively, and; which problems are difficult to solve in limited space. Formally, a decision problem …
127Social Security debate (United States) — This article concerns proposals to change the Social Security system in the United States. Social Security is a social insurance program officially called Old Age, Survivors, and Disability Insurance (OASDI), in reference to its three components …
128Economics of global warming — This article describes the economics of global warming and climate change. Contents 1 Definitions 2 Climate change science 3 Scenarios 4 Trends and projections …
