Lucid (programming language)

Lucid is a dataflow programming language. It is designed to experiment with non-von Neumann programming models. It was designed by Bill Wadge and Ed Ashcroft and described in the book Lucid, the Dataflow Programming Language.

Model

Lucid uses a demand-driven model for data computation. Each statement can be understood as an equation defining a network of processors and communication lines between them through which data flows. Each variable is an infinite stream of values and every function is a filter or a transformer. Iteration is simulated by 'current' values and 'fby' (read as 'followed by') operator allowing composition of streams.

Lucid is based on an algebra of histories, a history being an infinite sequence of data items. Operationally, a history can be thought of as a record of the changing values of a variable, history operations such as first and next can be understood in ways suggested by their names. Lucid was originally conceived as a kind of very disciplined, mathematically pure, single-assignment language, in which verification would be very much simplified. However, the dataflow interpretation has been a very important influence on the direction in which Lucid has evolved.

Lucid (film)

Lucid is a 2005 Canadian film written and directed by Sean Garrity. It won the award for Best Western Canadian Feature Film at the Vancouver International Film Festival in 2005 and it was nominated for Best Film at the Mannheim-Heidelberg International Film Festival in 2006.

Plot

Joel Rothman (Jonas Chernick) is suffering from insomnia after having massive problems in his personal life including a separation and being targeted by his boss. As a psychotherapist he is assigned three patients suffering from Post Traumatic Stress Disorder. He must treat them to figure out his own life.

External links

Lucid (album)

Lucid is the fifth studio album by American R&B singer Lyfe Jennings. The album was released on October 8, 2013, by Mass Appeal Entertainment. On May 8, 2013, the album's first single "Boomerang" was released. On July 25, 2013, the music video was released for "Boomerang".

Critical response

Lucid was met with a generally positive reviews from music critics. Andy Kellman of AllMusic gave the album three out of four stars, saying "Jennings draws character sketches, spins cautionary tales—as someone still growing, learning from his mistakes—and largely sticks to the type of mature R&B that his listeners don't get from anyone else. He briefly breaks from the norm with "Rock," a classy but contemporary steppers groove that's one of his best songs. Despite a mostly new cast of collaborators—including TGT associate Brandon Hodge and producer/songwriter Lashaunda "Babygirl" Carr—Lucid is a natural progression for a veteran artist who seems to have plenty left to express."

Track listing

Theory

Theory is a contemplative and rational type of abstract or generalizing thinking, or the results of such thinking. Depending on the context, the results might for example include generalized explanations of how nature works. The word has its roots in ancient Greek, but in modern use it has taken on several different related meanings. A theory is not the same as a hypothesis. A theory provides an explanatory framework for some observation, and from the assumptions of the explanation follows a number of possible hypotheses that can be tested in order to provide support for, or challenge, the theory.

A theory can be normative (or prescriptive), meaning a postulation about what ought to be. It provides "goals, norms, and standards". A theory can be a body of knowledge, which may or may not be associated with particular explanatory models. To theorize is to develop this body of knowledge.

As already in Aristotle's definitions, theory is very often contrasted to "practice" (from Greek praxis, πρᾶξις) a Greek term for "doing", which is opposed to theory because pure theory involves no doing apart from itself. A classical example of the distinction between "theoretical" and "practical" uses the discipline of medicine: medical theory involves trying to understand the causes and nature of health and sickness, while the practical side of medicine is trying to make people healthy. These two things are related but can be independent, because it is possible to research health and sickness without curing specific patients, and it is possible to cure a patient without knowing how the cure worked.

Chess theory

The game of chess is commonly divided into three phases: the opening, middlegame, and endgame. There is a large body of theory regarding how the game should be played in each of these phases, especially the opening and endgame. Those who write about chess theory, who are often but not necessarily also eminent players, are referred to as "theorists" or "theoreticians".

"Opening theory" commonly refers to consensus, broadly represented by current literature on the openings. "Endgame theory" consists of statements regarding specific positions, or positions of a similar type, though there are few universally applicable principles. "Middlegame theory" often refers to maxims or principles applicable to the middlegame. The modern trend, however, is to assign paramount importance to analysis of the specific position at hand rather than to general principles.

The development of theory in all of these areas has been assisted by the vast literature on the game. In 1913, preeminent chess historian H. J. R. Murray wrote in his 900-page magnum opus A History of Chess that, "The game possesses a literature which in contents probably exceeds that of all other games combined." He estimated that at that time the "total number of books on chess, chess magazines, and newspapers devoting space regularly to the game probably exceeds 5,000". In 1949, B. H. Wood opined that the number had increased to about 20,000.David Hooper and Kenneth Whyld wrote in 1992 that, "Since then there has been a steady increase year by year of the number of new chess publications. No one knows how many have been printed..." The world's largest chess library, the John G. White Collection at the Cleveland Public Library, contains over 32,000 chess books and serials, including over 6,000 bound volumes of chess periodicals. Chess players today also avail themselves of computer-based sources of information.

Theory (mathematical logic)

In mathematical logic, a theory (also called a formal theory) is a set of sentences in a formal language. Usually a deductive system is understood from context. An element of a theory is then called an axiom of the theory, and any sentence that follows from the axioms () is called a theorem of the theory. Every axiom is also a theorem. A first-order theory is a set of first-order sentences.

Theories expressed in formal language generally

When defining theories for foundational purposes, additional care must be taken and normal set-theoretic language may not be appropriate.

The construction of a theory begins by specifying a definite non-empty conceptual class , the elements of which are called statements. These initial statements are often called the primitive elements or elementary statements of the theory, to distinguish them from other statements which may be derived from them.

A theory is a conceptual class consisting of certain of these elementary statements. The elementary statements which belong to are called the elementary theorems of and said to be true. In this way, a theory is a way of designating a subset of which consists entirely of true statements.