SubgroupIn group theory, a branch of mathematics, given a group G under a binary operation ∗, a subset H of G is called a subgroup of G if H also forms a group under the operation ∗. More precisely, H is a subgroup of G if the restriction of ∗ to H × H is a group operation on H. This is often denoted H ≤ G, read as "H is a subgroup of G". The trivial subgroup of any group is the subgroup {e} consisting of just the identity element. A proper subgroup of a group G is a subgroup H which is a proper subset of G (that is, H ≠ G).
PropositionA proposition is a central concept in the philosophy of language, semantics, logic, and related fields, often characterized as the primary bearer of truth or falsity. Propositions are also often characterized as being the kind of thing that declarative sentences denote. For instance the sentence "The sky is blue" denotes the proposition that the sky is blue. However, crucially, propositions are not themselves linguistic expressions.
Normal subgroupIn abstract algebra, a normal subgroup (also known as an invariant subgroup or self-conjugate subgroup) is a subgroup that is invariant under conjugation by members of the group of which it is a part. In other words, a subgroup of the group is normal in if and only if for all and The usual notation for this relation is Normal subgroups are important because they (and only they) can be used to construct quotient groups of the given group.
Propositional calculusPropositional calculus is a branch of logic. It is also called propositional logic, statement logic, sentential calculus, sentential logic, or sometimes zeroth-order logic. It deals with propositions (which can be true or false) and relations between propositions, including the construction of arguments based on them. Compound propositions are formed by connecting propositions by logical connectives. Propositions that contain no logical connectives are called atomic propositions.
Mathematical proofA mathematical proof is a deductive argument for a mathematical statement, showing that the stated assumptions logically guarantee the conclusion. The argument may use other previously established statements, such as theorems; but every proof can, in principle, be constructed using only certain basic or original assumptions known as axioms, along with the accepted rules of inference. Proofs are examples of exhaustive deductive reasoning which establish logical certainty, to be distinguished from empirical arguments or non-exhaustive inductive reasoning which establish "reasonable expectation".
Propositional formulaIn propositional logic, a propositional formula is a type of syntactic formula which is well formed and has a truth value. If the values of all variables in a propositional formula are given, it determines a unique truth value. A propositional formula may also be called a propositional expression, a sentence, or a sentential formula. A propositional formula is constructed from simple propositions, such as "five is greater than three" or propositional variables such as p and q, using connectives or logical operators such as NOT, AND, OR, or IMPLIES; for example: (p AND NOT q) IMPLIES (p OR q).
Characteristic subgroupIn mathematics, particularly in the area of abstract algebra known as group theory, a characteristic subgroup is a subgroup that is mapped to itself by every automorphism of the parent group. Because every conjugation map is an inner automorphism, every characteristic subgroup is normal; though the converse is not guaranteed. Examples of characteristic subgroups include the commutator subgroup and the center of a group. A subgroup H of a group G is called a characteristic subgroup if for every automorphism φ of G, one has φ(H) ≤ H; then write H char G.
Lattice of subgroupsIn mathematics, the lattice of subgroups of a group is the lattice whose elements are the subgroups of , with the partial order relation being set inclusion. In this lattice, the join of two subgroups is the subgroup generated by their union, and the meet of two subgroups is their intersection. The dihedral group Dih4 has ten subgroups, counting itself and the trivial subgroup. Five of the eight group elements generate subgroups of order two, and the other two non-identity elements both generate the same cyclic subgroup of order four.
Propositional variableIn mathematical logic, a propositional variable (also called a sentential variable or sentential letter) is an input variable (that can either be true or false) of a truth function. Propositional variables are the basic building-blocks of propositional formulas, used in propositional logic and higher-order logics. Formulas in logic are typically built up recursively from some propositional variables, some number of logical connectives, and some logical quantifiers.
Propositional attitudeA propositional attitude is a mental state held by an agent or organism toward a proposition. In philosophy, propositional attitudes can be considered to be, neurally-realized causally efficacious content-bearing internal states (personal principles/values). Linguistically, propositional attitudes are denoted by a verb (e.g. "believed") governing an embedded "that" clause, for example, 'Sally believed that she had won'. Propositional attitudes are often assumed to be the fundamental units of thought and their contents, being propositions, are true or false from the perspective of the person.
Proof by contradictionIn logic, proof by contradiction is a form of proof that establishes the truth or the validity of a proposition, by showing that assuming the proposition to be false leads to a contradiction. Although it is quite freely used in mathematical proofs, not every school of mathematical thought accepts this kind of nonconstructive proof as universally valid. More broadly, proof by contradiction is any form of argument that establishes a statement by arriving at a contradiction, even when the initial assumption is not the negation of the statement to be proved.
Computer-assisted proofA computer-assisted proof is a mathematical proof that has been at least partially generated by computer. Most computer-aided proofs to date have been implementations of large proofs-by-exhaustion of a mathematical theorem. The idea is to use a computer program to perform lengthy computations, and to provide a proof that the result of these computations implies the given theorem. In 1976, the four color theorem was the first major theorem to be verified using a computer program.
Examples of groupsSome elementary examples of groups in mathematics are given on Group (mathematics). Further examples are listed here. Dihedral group of order 6 Consider three colored blocks (red, green, and blue), initially placed in the order RGB. Let a be the operation "swap the first block and the second block", and b be the operation "swap the second block and the third block". We can write xy for the operation "first do y, then do x"; so that ab is the operation RGB → RBG → BRG, which could be described as "move the first two blocks one position to the right and put the third block into the first position".
Martha Reeves (anchorite)Martha Reeves (born 1941) is a vowed Anglican solitary (or anchorite), with Rowan Williams, the former Archbishop of Canterbury, as bishop-protector. A graduate of the Madeira School (Class of 1959), she is also a Stanford-educated professor of theology who has written numerous articles and books under the name "Maggie Ross" as well as translated a number of Carthusian Novice Conferences. Reeves, at one time Desmond Tutu's spiritual director, was Bell Distinguished Professor in Anglican and Ecumenical Studies appointed to the Department of Philosophy and Religion, Kendall College of Arts and Sciences, The University of Tulsa.
Ken GoodmanKenneth Goodman (December 23, 1927 - March 12, 2020) was Professor Emeritus, Language Reading and Culture, at the University of Arizona. He is best known for developing the theory underlying the literacy philosophy of whole language. Goodman began teaching at Wayne State University in 1962. His research focused on reading in public schools. While at Wayne State University, Goodman developed miscue analysis, a process of assessing students' reading comprehension based on samples of oral reading.
University of Toronto SchoolsUniversity of Toronto Schools (UTS) is an independent secondary day school affiliated with the University of Toronto in Toronto, Ontario, Canada. The school follows a specialized academic curriculum, and admission is determined by competitive examination. UTS is associated with two Nobel Prize laureates. University of Toronto Schools was founded in 1910 as a "practice school", also known as a laboratory school, for the University of Toronto's Faculty of Education.
Justin TrudeauJustin Pierre James Trudeau (ˈtruːdoʊ,_truːˈdoʊ , ʒystɛ̃ pjɛʁ dʒɛms tʁydo; born December 25, 1971) is a Canadian politician serving as the 23rd and current prime minister of Canada since 2015 and leader of the Liberal Party since 2013. Trudeau is the second-youngest prime minister in Canadian history after Joe Clark; he is also the first to be the child of a previous holder of the post, as the eldest son of Pierre Trudeau. Trudeau was born in Ottawa and attended Collège Jean-de-Brébeuf.
Political positions of John McCainU.S. Senator John McCain, a Republican Party politician from Arizona who was a member of the U.S. Congress from 1983 until his death in office in 2018, a two-time U.S. presidential candidate, and the nominee of the Republican Party in the 2008 U.S. Presidential election, took positions on many political issues through his public comments, his presidential campaign statements, and his senatorial voting record. Online, McCain used his Senate web site and his 2008 campaign web site to describe his political positions.
Battle of Sept-ÎlesThe Battle of Sept-Îles was a naval action fought on the night of 22/23 October 1943 during World War II as part of the Atlantic campaign. The battle took place off the Sept-Îles near the French coast in the English Channel between a light cruiser and six destroyers of the British Royal Navy hoping to intercept, a German blockade runner, which was accompanied by German torpedo-boat destroyers flotillas of the German Kriegsmarine.
Sept-Îles, QuebecSept-Îles (Quebec French pronunciation : sɛ.t͡s‿ɪl, French for "Seven Islands") is a city in the Côte-Nord region of eastern Quebec. It is among the northernmost locales with a paved connection to the rest of Quebec's road network. The population was 25,686 as of the 2011 Canadian census. The town is called Uashat, meaning "bay" in Innu-aimun. The city is well known for having major iron companies like Iron Ore Company of Canada and the Cleveland-Cliffs mining company. The city relies heavily on the iron industry.
