| Olbers' paradox | 5BKWRGKK45 | statement | open | Wikipedia Hubble's law#W1D5 |
| Olbers' paradox | W0AMEA3Q0W | conjecture | open | Wikipedia Olbers' paradox, Wikidata Q33558 |
| Old and new representations of the polyconvex envelope | RRG73KQ5SF | example | record (an item of a paper that no node asks for yet. The record keeps its edges in the record plane (corpus arxiv AX8.6)) | arXiv 2606.21391#AIPZ |
| Old examples of automorphism groups | H3JEFS56C8 | example | open | napkin tex/alg-NT/galois.tex#example-5 |
| Old Fourth Ward | G668JC2DZ4 | unknown | open | Wikipedia List of places with numeric names#RTRJ |
| Old Hundred, North Carolina | AVAGZFMVGT | unknown | open | Wikipedia List of places with numeric names#VTJZ |
| Old quantum theory | XMYV62FQET | definition | open | Wikipedia Old quantum theory, Wikidata Q2566926 |
| Old World monkeys | 83FBD0PR9K | unknown | open | Wikipedia List of common misconceptions about science, technology, and mathematics#UCUS |
| Old-coordinate incidences in the principal part | ZX2T0ZE1FC | statement | record (an item of a paper that no node asks for yet. The record keeps its edges in the record plane (corpus arxiv AX8.6)) | arXiv 2609.25101#H44O |
| Older adults | 2WEEQDDHSW | unknown | open | Wikipedia List of common misconceptions about science, technology, and mathematics#NFJ0 |
| Oldroyd-B model | HMN8EZ6JZY | definition | open | Wikipedia Oldroyd-B model, Wikidata Q7085712 |
| Ole Barndorff-Nielsen | WN4C5339TD | topic | open | Wikipedia Ole Barndorff-Nielsen, Wikidata Q2018996 |
| Ole Ivar Lovaas | X5V9TB7XS2 | unknown | open | Wikipedia List of University of California, Los Angeles people#KEEF |
| Ole Jacob Broch | GWND5D7CT5 | unknown | open | Wikipedia List of actuaries#TTDE |
| Ole Michael Ludvigsen Selberg | M9CSCH33K4 | topic | open | Wikipedia Ole Michael Ludvigsen Selberg, Wikidata Q7085891 |
| Ole Peder Arvesen | 8S4R94CA3S | topic | open | Wikipedia Ole Peder Arvesen, Wikidata Q12717472 |
| Ole Peder Arvesen | VS1BB6BD5T | topic | open | Wikipedia List of mathematicians born in the 19th century#3FVH |
| Ole Skovsmose | 9GQ9FN8MRY | topic | open | Wikipedia Ole Skovsmose, Wikidata Q131917877 |
| Olech theorem | GB0NQTP59J | statement | open | Wikipedia Olech theorem, Wikidata Q42417350 |
| Oleg Besov | AJRGGTP7CJ | topic | open | Wikipedia Oleg Besov, Wikidata Q43323 |
| Oleg Izhboldin | DGSESQF56W | topic | open | Wikipedia Oleg Izhboldin, Wikidata Q65965960 |
| Oleg Lepski | H5ZM1YE87K | unknown | open | Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#V1UF |
| Oleg Lupanov | 1PV5VYTNEH | topic | open | Wikipedia Oleg Lupanov, Wikidata Q3710046 |
| Oleg Maisenberg | JYV0DJ32WS | unknown | open | Wikipedia List of Ukrainian Jews#7SEV |
| Oleg Marichev | HB3H5Y0Z4C | topic | open | Wikipedia Oleg Marichev, Wikidata Q1796816 |
| Oleg N. Ageev | 9V6AS44AXS | unknown | open | Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#T2EZ |
| Oleg Nagornov | WZKZDCWCV0 | topic | open | Wikipedia Oleg Nagornov, Wikidata Q23772335 |
| Oleg V Zaboronski | WAZPQ0MF4S | unknown | out_of_scope (a person, not an item of mathematics) | Wikidata Q79796639, nLab Oleg Zaboronsky |
| Oleg V. Besov | 201H7AGFMR | topic | open | Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#HYA4 |
| Oleg Viro | 7QV5Y0C0EE | topic | open | Wikipedia List of people by Erdős number#39GI |
| Oleg Viro | GF3MHX9YVF | topic | open | Wikipedia Oleg Viro, Wikidata Q2019237 |
| Oleg Yanovich Viro | NH4QS20ECA | topic | open | Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#AEEA |
| Oleg Yu. Emanouilov | B3N7SZKA58 | unknown | open | Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#J5OC |
| Oleksandr Feldman | HXG2QA5R9G | unknown | open | Wikipedia List of Ukrainian Jews#V7ZZ |
| Oleksii Bychenko | 1QADZCNRGQ | unknown | open | Wikipedia List of Ukrainian Jews#ORQD |
| Oleksii Reznikov | 4P8J7PH4CX | unknown | open | Wikipedia List of Ukrainian Jews#58Q9 |
| Olena Dvornichenko | BZ9PESCJTF | unknown | open | Wikipedia List of Ukrainian Jews#49CU |
| Olena Vaneeva | ACJFWGZ2G1 | topic | open | Wikipedia Olena Vaneeva, Wikidata Q65197035 |
| Olfactory | QRP61E8G4E | unknown | open | Wikipedia List of common misconceptions about science, technology, and mathematics#M3HJ |
| OLGA | DVE3M7YPPW | definition | open | Wikipedia OLGA (technology), Wikidata Q7072656 |
| Olga Beaver | FMJX0Y53NP | topic | open | Wikipedia Olga Beaver, Wikidata Q29616931 |
| Olga Bondareva | 648NDJQ8H5 | topic | open | Wikipedia Olga Bondareva, Wikidata Q4093138 |
| Olga Gil Medrano | 6WBHN9RCGZ | topic | open | Wikipedia Olga Gil Medrano, Wikidata Q6049813 |
| Olga Hahn-Neurath | ABZAG6KQQ4 | topic | open | Wikipedia List of women logicians#XMTD |
| Olga Hahn-Neurath | YJ5C1RC5G3 | topic | open | Wikipedia Olga Hahn-Neurath, Wikidata Q85932 |
| Olga Holtz | CQMCKHZBXZ | topic | open | Wikipedia Olga Holtz, Wikidata Q1699677 |
| Olga Kameneva | EMYHM7PK1G | unknown | open | Wikipedia List of Ukrainian Jews#ZONA |
| Olga Kharlampovich | 83AYV131QD | unknown | open | Wikipedia List of people by Erdős number#EBZ0, Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#WJCV |
| Olga Ladyzhenskaya | 5P31DE5DPD | topic | open | Wikipedia List of people by Erdős number#OE5A, Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#8IR9, Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#CN2S, Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#F3O2 |
| Olga Ladyzhenskaya | 8GTANDYK5F | topic | open | Wikipedia List of Russian mathematicians#0BWA |
| Olga Ladyzhenskaya | SE85ZAYG3E | topic | open | Wikipedia Olga Ladyzhenskaya, Wikidata Q450269 |
| Olga Oleinik | 2CZY7AFP9N | topic | open | Wikipedia Olga Oleinik, Wikidata Q457680 |
| Olga Oleinik | YM8FN7QGZ0 | topic | open | Wikipedia List of people by Erdős number#O982, Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#N5AX |
| Olga Pendleton | V03CW6P1J5 | unknown | open | Wikipedia List of fellows of the American Statistical Association#SL45 |
| Olga Rapay-Markish | P038FBNRZT | unknown | open | Wikipedia List of Ukrainian Jews#6FNM |
| Olga Taussky | 2SWY76W84F | unknown | open | Wikipedia List of Jewish mathematicians#FKZA |
| Olga Taussky-Todd | 4W23KSEF42 | unknown | open | Wikipedia List of people by Erdős number#DR22, Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#7TD3 |
| Olga Tsuberbiller | YN1W729HA9 | topic | open | Wikipedia Olga Tsuberbiller, Wikidata Q57573358 |
| Olga Vitek | JRTQ2GZZCD | unknown | open | Wikipedia List of fellows of the American Statistical Association#LS4Y |
| Olgica Milenkovic | QF9057FTDD | unknown | open | Wikipedia List of people by Erdős number#UPZM |
| Oligomorphic group | NHZN76CHCV | definition | open | Wikipedia List of permutation topics#SP7T |
| Oligomorphic group | RXTYBQWF9R | unknown | open | Wikipedia Permutation group#AL9Z |
| Olimpíada Brasileira de Matemática | ANZK4SY0SM | definition | open | Wikipedia List of mathematics competitions#RUKR |
| Olimpíada Brasileira de Matemática | NJWNEB0TR3 | definition | open | Wikipedia Olimpíada Brasileira de Matemática, Wikidata Q7086900 |
| Olimpíada Brasileira de Matemática das Escolas Públicas | 4N33TJYZCZ | unknown | open | Wikipedia List of mathematics competitions#8QXP |
| Olimpíada de Matemática do Grande ABC | RWHH9RXFPY | definition | open | Wikipedia Olimpíada de Matemática do Grande ABC, Wikidata Q28133949 |
| Olinde Rodrigues | BW0702R7VP | topic | open | Wikipedia List of Jewish mathematicians#DO2X |
| Olinde Rodrigues | EJJN7Q07EG | topic | open | Wikipedia List of eponyms of special functions#DR36 |
| Olinde Rodrigues | KSJSXV0QZP | topic | open | Wikipedia Olinde Rodrigues, Wikidata Q168405 |
| Olinthus Gregory | FX6847CDC5 | topic | open | Wikipedia Olinthus Gregory, Wikidata Q3710265 |
| Olive Clio Hazlett | 3BVXW4T1MZ | topic | open | Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#U92B |
| Olive Hazlett | CHW6GHXWXM | topic | open | Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#ZDJI |
| Olive Hazlett | S1FV89X0NM | topic | open | Wikipedia Olive Hazlett, Wikidata Q7087160 |
| Olive Jean Dunn | 3K1H6C4SA7 | topic | open | Wikipedia Olive Jean Dunn, Wikidata Q23585442 |
| Olive Jean Dunn | 8C5HY3QJ8R | topic | open | Wikipedia List of fellows of the American Statistical Association#5SQU |
| Oliver Byrne | Z6J8DYF70H | topic | open | Wikipedia Oliver Byrne (mathematician), Wikidata Q1739609 |
| Oliver Chinganya | HHMAHZC37E | topic | open | Wikipedia Oliver Chinganya, Wikidata Q118407847 |
| Oliver Edmunds Glenn | 6G2PDGB1ZA | topic | open | Wikipedia Oliver Edmunds Glenn, Wikidata Q7087512 |
| Oliver Edmunds Glenn | V64MV1FHAC | topic | open | Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#00QZ, Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#FFAZ, Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#MH85 |
| Oliver Heaviside | CGZV2QJ91K | topic | open | Wikipedia Oliver Heaviside, Wikidata Q154345 |
| Oliver Lorscheid | S6HWPE4ZCE | unknown | out_of_scope (a person, not an item of mathematics) | Wikidata Q102338869, nLab Oliver Lorscheid |
| Oliver Riordan | V6V8FJ757K | problem | open | Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#KTNU |
| Olivetti Summa Prima 20 | MKQZZE4QSQ | definition | open | Wikipedia Olivetti Summa Prima 20, Wikidata Q16583870 |
| Olivia Caramello | RK3P44756N | topic | open | Wikipedia Olivia Caramello, Wikidata Q102361389 |
| Olivier Biquard | KVFDFEK65G | unknown | open | Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#I2HN |
| Olivier Guéant | ZX2E123QZJ | topic | open | Wikipedia Olivier Guéant, Wikidata Q24950692 |
| Olivier Mathieu | JG3SA72JFX | unknown | open | Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#LLGI |
| Olivier Pironneau | HFBBX7MTZ9 | topic | open | Wikipedia Olivier Pironneau, Wikidata Q3351286 |
| Olivier Ramaré | JS2ZDEDQRN | topic | open | Wikipedia Olivier Ramaré, Wikidata Q3292746 |
| Olivier Ramaré | Y6F9EVWTN1 | topic | open | Wikipedia List of people by Erdős number#PZ9X |
| Olivier Rey | K77E25B7Q1 | topic | open | Wikipedia Olivier Rey, Wikidata Q3351331 |
| Olivier Schiffmann | JCW8NF11AX | unknown | open | Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#UFTU |
| Olivier Verdier | G5YCJQTWTF | unknown | out_of_scope (a person, not an item of mathematics) | Wikidata Q87394918, nLab Olivier Verdier |
| Olivier Wittenberg | FSC7TC5CXR | unknown | open | Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#9QJJ |
| Olle Häggström | 1S0ASHPSQ2 | topic | open | Wikipedia Olle Häggström, Wikidata Q5819438 |
| Olli Lehto | 8T9GTSXRGJ | topic | open | Wikipedia Olli Lehto, Wikidata Q1459204 |
| Olli Lehto | VJ15ZYD3ZQ | topic | open | Wikipedia List of people by Erdős number#50OU, Wikipedia List of International Congresses of Mathematicians Plenary and Invited Speakers#NK0I |
| Olli Lokki | PHX3BF976T | topic | open | Wikipedia Olli Lokki, Wikidata Q17382283 |
| Ollivier-Ricci curvature | XG5ZRQFEKH | definition | record (an item of a paper that no node asks for yet. The record keeps its edges in the record plane (corpus arxiv AX8.6)) | arXiv 2610.10559#JLTA |
| Olm (encryption protocol) | 65QR2ZX4G5 | unknown | open | Wikipedia Matrix (protocol)#8E3Y |