# Sunday Iyahen

Sunday Osarumwense Iyahen (3 October 1937 – 28 January 2018) was a Nigerian mathematician and politician, recognised for his contributions to the field of topological vector spaces and his service as a senator representing Bendel Central Senatorial District. Born in Benin City, Edo State, Nigeria, Iyahen was the eldest of at least seventeen children and embarked on an academic journey that led him to earn a first-class honours degree in mathematics from the University of Ibadan and later a Ph.D. and D.Sc. from the University of Keele.
Iyahen's academic career was marked by his tenure as a professor of mathematics at several universities in Nigeria and abroad. He served as the Head of the Department of Mathematics and Dean of the Faculty of Science at the University of Ibadan before joining the Institute of Technology, Benin (now known as the University of Benin), where he became the founding dean of the Faculty of Physical Sciences. His scholarly work includes over 100 published papers and contributions as editor-in-chief for mathematical journals. He was honoured with fellowships from the Nigerian Academy of Science and the Mathematical Association of Nigeria. As a politician, he was elected as a senator, where he contributed to national policy and development.

## Early life and education

Iyahen was born on 3 October 1937 in Benin City, Edo State, Nigeria. He was the eldest of at least seventeen children of Solomon Igbinuwen Iyahen and his wife Aiwekhoe.
Iyahen attended Saint Matthew's Primary school (1944–45), and Saint Peter's School (1945–51) in Benin City. Both schools were under the administration of the Church Mission Society, a London-based organisation established in 1799. He then attended Edo College. In 1956, he passed in the Cambridge school certificate examination, earning a Division One. He studied at Government College, Ibadan, for his Cambridge Higher School Certificate in 1957–1958.
In 1959, he enrolled at University College, Ibadan, and graduated with a first class honours degree in mathematics in 1963. He then proceeded to the University of Keele, where he obtained his Ph.D. in mathematics in 1967. He later obtained his D.Sc. in mathematics from the same university in 1987.

## Academic career

Iyahen commenced his academic journey as a mathematics lecturer at the University of Ibadan in 1965. He progressed through the ranks, achieving senior lecturer status in 1969 and professorship in 1974. He was the Head of Department for Mathematics from 1976 to 1978 and Dean of the Faculty of Science from 1978 to 1980.
In 1980, he joined the Institute of Technology, Benin (later renamed the University of Benin), where he served as the founding dean of the Faculty of Physical Sciences and director of the Centre for Mathematical Sciences, Abuja, Nigeria. Additionally, he held the position of vice-chancellor from 1985 to 1986. He contributed as a visiting professor to various institutions, including the University of Lagos, University of Jos, University of Port Harcourt, University of Ilorin, University of Nigeria, Nsukka, University of Cape Coast, University of Khartoum, and the University of Waterloo.
He published over 100 mathematics-related papers in international journals, served as the editor-in-chief for Afrika Mathematika and Journal of the Nigerian Mathematical Society, and chaired the board of Federal Polytechnic, Idah. He was a fellow of the Nigerian Academy of Science and the Mathematical Association of Nigeria, Iyahen was also a member of the London Mathematical Society, the American Mathematical Society, and the International Mathematical Union.

## Political career

Iyahen was a two-time senator of the Federal Republic of Nigeria. He represented Bendel Central Senatorial District under the platform of the National Party of Nigeria (NPN) in the second republic (October to December 1983) and the Social Democratic Party (SDP) in the third republic (August 1992 to November 1993). He served in different capacities in the senate, such as the chairman of the Committee on Education, Science and Technology, and the vice-chairman of the Committee on Finance and Appropriation.

## Personal life and death

Iyahen married Veronica Aigboduwa Osagie on 25 September 1967. They had six children and eleven grandchildren. Iyahen died on 28 January 2018 in Benin City, Edo State, Nigeria. He was buried on 16 February 2018 at his residence in Benin City.

## Selected publications

* ——— (1967). "Some remarks on countably barrelled and countably quasibarrelled spaces". Proceedings of the Edinburgh Mathematical Society. 15 (4). Cambridge University Press (CUP): 295–296. doi:10.1017/s0013091500011949. ISSN 0013-0915.
* ——— (30 September 2017). "Mathematics, Science, And Cultural Change". Proceedings of the Nigerian Academy of Science. 10 (1). Nigerian Academy of Science. doi:10.57046/eqbu2235. ISSN 0794-7976.
* ——— (11 August 2010). "Boundedly barrelled spaces and the open mapping theorem". Portugaliae Mathematica. 46 (3). Sociedade Portuguesa de Matemática: 305–312. ISSN 0032-5155.
* ——— (1978). "The range space in a closed graph theorem". Acta Mathematica Academiae Scientiarum Hungaricae. 32 (1–2). Springer Science and Business Media LLC: 17–20. doi:10.1007/bf01902196. ISSN 0001-5954.
* ——— (1968). "Semiconvex spaces". Glasgow Mathematical Journal. 9 (2). Cambridge University Press (CUP): 111–118. doi:10.1017/s0017089500000380. ISSN 0017-0895.
* ——— (1969). "Semiconvex spaces II". Glasgow Mathematical Journal. 10 (2). Cambridge University Press (CUP): 103–105. doi:10.1017/s001708950000063x. ISSN 0017-0895.
* ——— (1972). "A note on the filter condition". Acta Mathematica Academiae Scientiarum Hungaricae. 23 (3–4): 271–274. doi:10.1007/BF01896945. ISSN 0001-5954.
* ——— (1968). "-spaces and the closed-graph theorem". Proceedings of the Edinburgh Mathematical Society. 16 (2). Cambridge University Press (CUP): 89–99. doi:10.1017/s0013091500012463. ISSN 0013-0915.
* ———; Popoola, J. O. (1973). "A generalized inductive limit topology for linear spaces". Glasgow Mathematical Journal. 14 (2). Cambridge University Press (CUP): 105–110. doi:10.1017/s001708950000183x. ISSN 0017-0895.
* ——— (1971). "Bounded generators in linear topological spaces". Glasgow Mathematical Journal. 12 (2). Cambridge University Press (CUP): 105–109. doi:10.1017/s001708950000121x. ISSN 0017-0895.
* ——— (1969). "Ultrabarrelled groups and the closed graph theorem". Mathematical Proceedings of the Cambridge Philosophical Society. 65 (1). Cambridge University Press (CUP): 53–58. Bibcode:1969PCPS...65...53I. doi:10.1017/s0305004100044078. ISSN 0305-0041.