City-stateA city-state is an independent sovereign city which serves as the center of political, economic, and cultural life over its contiguous territory. They have existed in many parts of the world since the dawn of history, including ancient poleis such as Athens, Sparta, Carthage and Rome, and the Italian city-states during the Middle Ages and Renaissance, such as Florence, Venice, Genoa and Milan. With the rise of nation states worldwide, there remains some disagreement on the number of modern city-states that still exist; Singapore, Monaco and Vatican City are the candidates most commonly discussed.
Expert systemIn artificial intelligence, an expert system is a computer system emulating the decision-making ability of a human expert. Expert systems are designed to solve complex problems by reasoning through bodies of knowledge, represented mainly as if–then rules rather than through conventional procedural code. The first expert systems were created in the 1970s and then proliferated in the 1980s. Expert systems were among the first truly successful forms of artificial intelligence (AI) software.
New YearNew Year is the time or day at which a new calendar year begins and the calendar's year count increments by one. Many cultures celebrate the event in some manner. In the Gregorian calendar, the most widely used calendar system today, New Year occurs on January 1 (New Year's Day, preceded by New Year's Eve). This was also the first day of the year in the original Julian calendar and the Roman calendar (after 153 BC).
Indicative planningIndicative planning is a form of economic planning implemented by a state in an effort to solve the problem of imperfect information in market economies by coordination of private and public investment through forecasts and output targets. The resulting plans aim to supply economically valuable information as a public good that the market by itself cannot disseminate, or where forward markets are nonexistent. However, indicative planning takes only endogenous market uncertainty into account, plans the economy accordingly, and does not look into exogenous uncertainty like technology, foreign trade, etc.
World-systems theoryWorld-systems theory (also known as world-systems analysis or the world-systems perspective) is a multidisciplinary approach to world history and social change which emphasizes the world-system (and not nation states) as the primary (but not exclusive) unit of social analysis. "World-system" refers to the inter-regional and transnational division of labor, which divides the world into core countries, semi-periphery countries, and the periphery countries.
Tropical yearA tropical year or solar year (or tropical period) is the time that the Sun takes to return to the same position in the sky of a celestial body of the Solar System such as the Earth, completing a full cycle of seasons; for example, the time from vernal equinox to vernal equinox, or from summer solstice to summer solstice. It is the type of year used by tropical solar calendars. The solar year is one type of astronomical year and particular orbital period.
Hunter-gathererA traditional hunter-gatherer or forager is a human living an ancestrally derived lifestyle in which most or all food is obtained by foraging, that is, by gathering food from local naturally occurring sources, especially edible wild plants but also insects, fungi, honey, bird eggs, or anything safe to eat, and/or by hunting game (pursuing and/or trapping and killing wild animals, including catching fish). This is a common practice among most omnivores.
Well-founded relationIn mathematics, a binary relation R is called well-founded (or wellfounded or foundational) on a class X if every non-empty subset S ⊆ X has a minimal element with respect to R, that is, an element m ∈ S not related by s R m (for instance, "s is not smaller than m") for any s ∈ S. In other words, a relation is well founded if Some authors include an extra condition that R is set-like, i.e., that the elements less than any given element form a set.
Lucid dreamA lucid dream is a type of dream in which the dreamer becomes aware that they are dreaming while dreaming. During a lucid dream, the dreamer may gain some amount of control over the dream characters, narrative, or environment. Lucid dreaming has been studied and reported for many years. Prominent figures from ancient to modern times have been fascinated by lucid dreams and have sought ways to better understand their causes and purpose. Many different theories have emerged as a result of scientific research on the subject and have even been shown in pop culture.
State religionA state religion (also called official religion) is a religion or creed officially endorsed by a sovereign state. A state with an official religion (also known as confessional state or religious state), while not a secular state, is not necessarily a theocracy. State religions are official or government-sanctioned establishments of a religion, but the state does not need to be under the control of the clergy (as in a theocracy), nor is the state-sanctioned religion necessarily under the control of the state.
