Question: Are Ivan Fesenko and Boris Trakhtenbrot both mathematicians?

Context paragraphs:
Cinderella (Fitinhof-Schell): Cinderella (ru.  «Золушка», "Zolushka") (fr.  "Cendrillon") is a "ballet-féerie" in three acts, with the choreographyof Enrico Cecchetti (Acts I and III) and Lev Ivanov (Act II) supervised by Marius Petipa.  Music is by Baron Boris Fitinhoff-Schell; the libretto is by Lidia Pashkova (ru: Лидия Александровна Пашкова) and Ivan Vsevolozhsky.  It was first presented by the Imperial Ballet on 17 December [O.S. 5 December] 1893 at the Imperial Mariinsky Theatre in St. Petersburg, Russian Empire.

Fesenko group: In mathematics, Fesenko groups are certain subgroups of the wild automorphism groups of local fields of positive characteristic (i.e. the Nottingham group), studied by Ivan Fesenko ().

Russian literature: Russian literature refers to the literature of Russia and its émigrés and to the Russian-language literature of several independent nations once a part of what was historically Rus', the Russian Empire or the Soviet Union.  The roots of Russian literature can be traced to the Middle Ages, when epics and chronicles in Old Russian were composed.  By the Age of Enlightenment, literature had grown in importance, and from the early 1830s, Russian literature underwent an astounding golden age in poetry, prose and drama.  Romanticism permitted a flowering of poetic talent: Vasily Zhukovsky and later his protégé Alexander Pushkin came to the fore.  Prose was flourishing as well.  The first great Russian novelist was Nikolai Gogol.  Then came Ivan Turgenev, who mastered both short stories and novels.  Leo Tolstoy and Fyodor Dostoyevsky soon became internationally renowned.  In the second half of the century Anton Chekhov excelled in short stories and became a leading dramatist.  The beginning of the 20th century ranks as the Silver Age of Russian poetry.  The poets most often associated with the "Silver Age" are Konstantin Balmont, Valery Bryusov, Alexander Blok, Anna Akhmatova, Nikolay Gumilyov, Osip Mandelstam, Sergei Yesenin, Vladimir Mayakovsky, Marina Tsvetaeva and Boris Pasternak.  This era produced some first-rate novelists and short-story writers, such as Aleksandr Kuprin, Nobel Prize winner Ivan Bunin, Leonid Andreyev, Fyodor Sologub, Aleksey Remizov, Yevgeny Zamyatin, Dmitry Merezhkovsky and Andrei Bely.

Trakhtenbrot's theorem: In logic, finite model theory, and computability theory, Trakhtenbrot's theorem (due to Boris Trakhtenbrot) states that the problem of validity in first-order logic on the class of all finite models is undecidable.  In fact, the class of valid sentences over finite models is not recursively enumerable (though it is co-recursively enumerable).

John B. Balinsky: John (Ivan) Boris Balinsky (July 4, 1934 in Kyiv, Ukrainian SSR – October 1, 1983 in Ames, Iowa, Iowa, United States) - South African and American zoologist of Ukrainian origin.  His father Boris Balinsky was an embryologist.

Ivan Urgant: Ivan Andreevich Urgant (Russian: Ива́н Андре́евич У́ргант ; (born 16 April 1978) is a Russian television host, presenter, actor, musician and producer.  His best known roles in film are Boris in the "Yolki" series and as Danila in "Lucky Trouble".  Since 2012 he has hosted "Evening Urgant", a late-night talk show.  According to the 2008 and 2011 surveys, Ivan Urgant is Russia's most popular TV presenter.

Ivan Fesenko: Ivan Fesenko (Russian: Иван Борисович Фесенко ; born 1962) is a mathematician working in number theory and other areas of modern mathematics.

The Death of Ivan the Terrible: The Death of Ivan the Terrible (Russian: Смерть Иоанна Грозного, "Smert Ioa′nna Gro′znogo" ) is a historical drama by Aleksey Konstantinovich Tolstoy written in 1863 and first published in the January 1866 issue of "Otechestvennye zapiski" magazine.  It is the first part of a trilogy that is followed by "Tsar Fiodor Ioannovich" and concludes with "Tsar Boris".  All three plays were banned by the censor.  It dramatises the story of Ivan IV of Russia and is written in blank verse.  Tolstoy was influenced by the work of William Shakespeare in writing the trilogy, which formed the core of his reputation as a writer in the Russia of his day and as a dramatist to this day.

Boris Trakhtenbrot: Boris (Boaz) Avraamovich Trakhtenbrot (Russian: Борис Авраамович Трахтенброт ; 19 February 1921 – 19 September 2016), or Boaz (Boris) Trakhtenbrot (Hebrew: בועז טרכטנברוט‎ ‎ ) was an Israeli and Russian mathematician in mathematical logic, algorithms, theory of computation, and cybernetics.  Trakhtenbrot was born in Brichevo, northern Bessarabia.  He worked at Akademgorodok, Novosibirsk during the 1960s and 1970s.

Byzantine–Hungarian War (1127–29): A Byzantine–Hungarian War was fought between Byzantine and Hungarian forces on the Danube between 1127 and 1129.  According to the Byzantine chronicler Niketas Choniates, the citizens of the Byzantine town Braničevo "attacked and plundered the Hungarians who had come to" the Byzantine Empire "to trade, perpetrating the worst crimes against them."  Stephen II of Hungary broke into the empire in the summer.  His troops sacked Belgrade, Braničevo and Niš, and plundered the regions around Serdica (Sofia, Bulgaria) and Philippopolis (Plovdiv, Bulgaria), before returning to Hungary.  In response, Emperor John II marched against Hungary in 1128, where he defeated the royal troops in a battle at Haram, and "captured Frangochorion, the richest land in Hungary" (now in Serbia).  Following his victory over the Hungarians John II launched a punitive raid against the Serbs.  Dangerously for the Byzantines the Serbs had aligned themselves with Hungary.  Many Serbian prisoners were taken, and these were transported to Nicomedia in Asia Minor to serve as military colonists.  This was done partly to cow the Serbs into submission (Serbia was, at least nominally, a Byzantine protectorate), and partly to strengthen the Byzantine frontier in the east against the Turks.  The Serbs were forced to acknowledge Byzantine suzerainty once again.  In Hungary, the defeat at Haram undermined Stephen II's authority and he faced a serious revolt when two counts, named 'Bors' (possibly Boris Kalamanos) and 'Ivan', were declared kings.  Both were eventually defeated, Ivan being beheaded and Bors fleeing to Byzantium.  Stephen was unable to participate in any of the fighting because he was sick, recuperating in his homeland, according to John Kinnamos.  John Kinnamos wrote of a second campaign by Stephen against the Byzantine Empire, when the Hungarian troops, supported by Bohemian reinforcements under the command of Duke Václav of Olomouc, took Braničevo by storm and destroyed its fortress.  The Hungarians had renewed hostilities, possibly in order that King Stephen could be seen to reassert his authority, by attacking the Byzantine frontier fortress of Braničevo, which was immediately rebuilt by John.  Further Byzantine military successes – Choniates mentions several engagements – resulted in a restoration of peace.  Cinnamus describes a Byzantine reverse occurring before peace was established, which suggests that the campaign was not entirely one-sided.  Hungarian records, however, agree with Choniates in indicating that King Stephen was again defeated and was consequently forced to negotiate a peace on Byzantine terms.  Historian Ferenc Makk thinks that Emperor John II Komnenos was forced to retreat and sue for peace and that the treaty was signed in October 1129.  The Byzantines were confirmed in their control of Braničevo, Belgrade, and Zemun and they also recovered the region of Syrmia (called Frangochorion in Choniates), which had been in Hungarian hands since the 1060s.  The Hungarian pretender Álmos died in 1129, removing the major source of friction.

Supporting paragraphs: Ivan Fesenko Boris Trakhtenbrot
Answer: yes