Alexander Arhangelskii
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Alexander Vladimirovich Arhangelskii (russian: Александр Владимирович Архангельский, ''Aleksandr Vladimirovich Arkhangelsky'', born 13 March 1938 in
Moscow Moscow ( , US chiefly ; rus, links=no, Москва, r=Moskva, p=mɐskˈva, a=Москва.ogg) is the capital and largest city of Russia. The city stands on the Moskva River in Central Russia, with a population estimated at 13.0 million ...
) is a
Russian Russian(s) refers to anything related to Russia, including: *Russians (, ''russkiye''), an ethnic group of the East Slavic peoples, primarily living in Russia and neighboring countries *Rossiyane (), Russian language term for all citizens and peo ...
mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...
. His research, comprising over 200 published papers, covers various subfields of
general topology In mathematics, general topology is the branch of topology that deals with the basic set-theoretic definitions and constructions used in topology. It is the foundation of most other branches of topology, including differential topology, geomet ...
. He has done particularly important work in metrizability theory and generalized
metric space In mathematics, a metric space is a set together with a notion of ''distance'' between its elements, usually called points. The distance is measured by a function called a metric or distance function. Metric spaces are the most general settin ...
s,
cardinal function In mathematics, a cardinal function (or cardinal invariant) is a function that returns cardinal numbers. Cardinal functions in set theory * The most frequently used cardinal function is a function that assigns to a set ''A'' its cardinality, den ...
s, topological
function space In mathematics, a function space is a set of functions between two fixed sets. Often, the domain and/or codomain will have additional structure which is inherited by the function space. For example, the set of functions from any set into a vect ...
s and other
topological group In mathematics, topological groups are logically the combination of groups and topological spaces, i.e. they are groups and topological spaces at the same time, such that the continuity condition for the group operations connects these two str ...
s, and special classes of topological maps. After a long and distinguished career at
Moscow State University M. V. Lomonosov Moscow State University (MSU; russian: Московский государственный университет имени М. В. Ломоносова) is a public research university in Moscow, Russia and the most prestigious ...
, he moved to the United States in the 1990s. In 1993 he joined the faculty of
Ohio University Ohio University is a Public university, public research university in Athens, Ohio. The first university chartered by an Act of Congress and the first to be chartered in Ohio, the university was chartered in 1787 by the Congress of the Confeder ...
, from which he retired in 2011.


Biography

Arhangelskii was the son of Vladimir Alexandrovich Arhangelskii and Maria Pavlova Radimova, who divorced by the time he was four years old. He was raised in Moscow by his father. He was also close to his uncle, childless aircraft designer Alexander Arkhangelsky. In 1954, Arhangelskii entered Moscow State University, where he became a student of
Pavel Alexandrov Pavel Sergeyevich Alexandrov (russian: Па́вел Серге́евич Алекса́ндров), sometimes romanized ''Paul Alexandroff'' (7 May 1896 – 16 November 1982), was a Soviet mathematician. He wrote about three hundred papers, ma ...
. At the end of his first year, Arhangelskii told Alexandrov that he wanted to specialize in
topology In mathematics, topology (from the Greek language, Greek words , and ) is concerned with the properties of a mathematical object, geometric object that are preserved under Continuous function, continuous Deformation theory, deformations, such ...
. In 1959, in the thesis he wrote for his
specialist degree The specialist degree is an academic degree conferred by a college or university. The degree is formatted differently worldwide and may be either a five-year program or a doctoral level graduate program that occurs after a master's degree but befo ...
, he introduced the concept of a ''network'' of a
topological space In mathematics, a topological space is, roughly speaking, a geometrical space in which closeness is defined but cannot necessarily be measured by a numeric distance. More specifically, a topological space is a set whose elements are called points ...
. Now considered a fundamental topological notion, a network is a collection of subsets that is similar to a
basis Basis may refer to: Finance and accounting * Adjusted basis, the net cost of an asset after adjusting for various tax-related items *Basis point, 0.01%, often used in the context of interest rates * Basis trading, a trading strategy consisting ...
, without the requirement that the sets be
open Open or OPEN may refer to: Music * Open (band), Australian pop/rock band * The Open (band), English indie rock band * ''Open'' (Blues Image album), 1969 * ''Open'' (Gotthard album), 1999 * ''Open'' (Cowboy Junkies album), 2001 * ''Open'' (YF ...
. Also in 1959 he married Olga Constantinovna. He received his
Candidate of Sciences Candidate of Sciences (russian: кандидат наук, translit=kandidat nauk) is the first of two doctoral level scientific degrees in Russia and the Commonwealth of Independent States. It is formally classified as UNESCO's ISCED level 8, "do ...
degree (equivalent to a Ph.D.) in 1962 from the
Steklov Institute of Mathematics Steklov Institute of Mathematics or Steklov Mathematical Institute (russian: Математический институт имени В.А.Стеклова) is a premier research institute based in Moscow, specialized in mathematics, and a part ...
, supervised by Alexandrov. He was granted the
Doctor of Sciences Doctor of Sciences ( rus, доктор наук, p=ˈdoktər nɐˈuk, abbreviated д-р наук or д. н.; uk, доктор наук; bg, доктор на науките; be, доктар навук) is a higher doctoral degree in the Russi ...
degree in 1966. It was in 1969 that Arhangelskii published what is considered his most significant mathematical result. Solving a problem posed in 1923 by Alexandrov and
Urysohn Pavel Samuilovich Urysohn () (February 3, 1898 – August 17, 1924) was a Soviet mathematician who is best known for his contributions in dimension theory, and for developing Urysohn's metrization theorem and Urysohn's lemma, both of which are f ...
, he proved that a
first-countable In topology, a branch of mathematics, a first-countable space is a topological space satisfying the "first axiom of countability". Specifically, a space X is said to be first-countable if each point has a countable neighbourhood basis (local base) ...
,
compact Compact as used in politics may refer broadly to a pact or treaty; in more specific cases it may refer to: * Interstate compact * Blood compact, an ancient ritual of the Philippines * Compact government, a type of colonial rule utilized in British ...
Hausdorff space In topology and related branches of mathematics, a Hausdorff space ( , ), separated space or T2 space is a topological space where, for any two distinct points, there exist neighbourhoods of each which are disjoint from each other. Of the many ...
must have a
cardinality In mathematics, the cardinality of a set is a measure of the number of elements of the set. For example, the set A = \ contains 3 elements, and therefore A has a cardinality of 3. Beginning in the late 19th century, this concept was generalized ...
no greater than the
continuum Continuum may refer to: * Continuum (measurement), theories or models that explain gradual transitions from one condition to another without abrupt changes Mathematics * Continuum (set theory), the real line or the corresponding cardinal number ...
. In fact, his theorem is much more general, giving an upper bound on the cardinality of any Hausdorff space in terms of two cardinal functions. Specifically, he showed that for any Hausdorff space ''X'', :, X, \le 2^ where χ(''X'') is the
character Character or Characters may refer to: Arts, entertainment, and media Literature * ''Character'' (novel), a 1936 Dutch novel by Ferdinand Bordewijk * ''Characters'' (Theophrastus), a classical Greek set of character sketches attributed to The ...
, and L(''X'') is the Lindelöf number. Chris Good referred to Arhangelskii's theorem as an "impressive result", and "a model for many other results in the field." Richard Hodel has called it "perhaps the most exciting and dramatic of the difficult inequalities", a "beautiful inequality", and "the most important inequality in
cardinal invariant In mathematics, a cardinal function (or cardinal invariant) is a function (mathematics), function that returns cardinal numbers. Cardinal functions in set theory * The most frequently used cardinal function is a function that assigns to a Set (m ...
s." In 1970 Arhangelskii became a full professor, still at Moscow State University. He spent 1972–75 on leave in
Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...
, teaching at the University of Islamabad under a
UNESCO The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations (UN) aimed at promoting world peace and security through international cooperation in education, arts, sciences and culture. It ...
program. Arhangelskii took advantage of the few available opportunities to travel to mathematical conferences outside of the Soviet Union. He was at a conference in
Prague Prague ( ; cs, Praha ; german: Prag, ; la, Praga) is the capital and largest city in the Czech Republic, and the historical capital of Bohemia. On the Vltava river, Prague is home to about 1.3 million people. The city has a temperate ...
when the
1991 Soviet coup d'état attempt The 1991 Soviet coup d'état attempt, also known as the August Coup,, "August Putsch". was a failed attempt by hardliners of the Soviet Union's Communist Party to forcibly seize control of the country from Mikhail Gorbachev, who was Soviet ...
took place. Returning under very uncertain conditions, he began to seek academic opportunities in the United States. In 1993 he accepted a professorship at Ohio University, where he received the
Distinguished Professor Distinguished Professor is an academic title given to some top tenured professors in a university, school, or department. Some distinguished professors may have endowed chairs. In the United States Often specific to one institution, titles such ...
Award in 2003. Arhangelskii was one of the founders of the journal '' Topology and its Applications'', and volume 153 issue 13, July 2006, was a special issue, with most of the papers based on talks given at a special conference held at
Brooklyn College Brooklyn College is a public university in Brooklyn, Brooklyn, New York. It is part of the City University of New York system and enrolls about 15,000 undergraduate and 2,800 graduate students on a 35-acre campus. Being New York City's first publ ...
30 June–3 July 2003 in honor of his 65th birthday.


Selected publications


Books

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Papers

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References


External links


Personal profile
at Ohio University * * {{DEFAULTSORT:Arhangelskii, Alexander 1938 births Living people Moscow State University alumni Moscow State University faculty Ohio University faculty Mathematicians from Moscow Topologists Russian expatriates in the United States Soviet mathematicians