Random

Blackboard Shots

Recent prefixes: Hogan 26-1301 Murugesan Enriquez 25-347 Martchenkov SantosK VanDerVeen Dancso Kuno Zammit RobertsonM 25-1301 Itai KAL 24-327

All prefixes: 08401 09240 10_327 11_1100 12_240 12_267 14_1100 15-344 15-475 16-1750 16-475 1617-257 17-1750 18-327 18S-AKT 2122-257 24-327 25-1301 25-347 26-1301 AKT09 AKT14 AKT17 Aarhus Abbasi Accra2010 Afeke Alekseev Alexakis Alhawaj Andersen Antolin Archibald BCHKW Bazett Beliakova Bellingeri Bettencourt Bigelow Blazejewski Boden Boninger Bosch Boyle Brin Brochier BrownF Bryden Burgos Caen Carrasco Carter Cattaneo Cheng Chterental Chu Cimasoni Conant Costantino Costello Dalvit Dancso Dema Deng Dolgushev Dror Enriquez Ens Etingof Faifman Fiedler Filmus Freedman Fresse Frohlich Frohman Furusho Gadanidis Gallagher Gaudreau Getzler Godin Gualtieri Gupta Halacheva Henriques Hillman Hirasawa Hoell Hogan Humbert Hurd Itai Izmaylov Jiang JohnsonFreyd KAL Kalka Kamnitzer Karshon Kashaev Katz Kauffman Kazhdan KhesinA Khovanov Kirk Koytcheff Kricker Kuno Kuperberg Lai Lambrechts Lauda LazyKnots Le LeD Ledvinka LeeP Leung LiBland LicataT LiuJ LopezNeumann Martchenkov Martel Martins Masbaum Massuyeau Matviichuk McKay McLellan Medabalimi Meusburger Mirny Miyazawa MorganS Morrison Morton-Ferguson Moskovich Mracek Munasinghe MurakamiJ Murphy Murugesan Naef Nandakumar Nikolaev Ohtsuki Olah Orr Overbay Papakonstantinou Peng Penneys PoleDancing PolyPoly-1605 Polyak Putyra Ramakrishna Rasmussen Raynor Reed Remenik Reshetikhin RobertsonM Roukema Rushworth Samuelson SantosK Sazdanovic Schaveling Scherich Schneps Sela Selmani Severa Smirnov Spreer Stein Sternberg SummerHomology2017 Suzuki TangYC Thimotheus ThurstonD ToledanoLaredo Tsimerman VanDerVeen Vaughan Vergne VideoClub Vo WangH Willwacher Winter Yampolsky Yetter Zammit ZeilbergerN Zhang Zibrowius Zung deSilva wClips

Date-Time / Prefix Comment What? A collection of Blackboard Shots (8598, right now, with 205 prefixes), mostly taken in my office using a ceiling-mounted web camera.
Why? Mostly for my own use and for the use of the other people with whom I share blackboard space. And it is public because the easiest way to make something viewable to a number of people is to make it viewable to the whole world.
Oh no! If you found your handwriting here and you don't like it, please let me know and the relevant shot(s) will be removed, no questions asked.
How? A ceiling-mounted Logitech QuickCam Pro 9000 web camera is permanently pointed at my blackboard and connected via USB to this web server. The script bbs.php initiates a capture (using luvcview; hit "s" to shoot and "q" to quit), prompts for a file name prefix and a comment, and runs make. The makefile runs MakeDatabase.php (if necessary) to update the ShotDatabase.php. The latter file is used by index.php, which is this page, and also by show.php, used to display individual shots. The makefile also updates bbs.zip, which contains all the above mentioned scripts as well as common.php, showprefix.php, loadnew.php, random.php, the JavaScript actions.js, and the icon bbs.jpg. Finally, $\TeX$-like rendering uses MathJax (automatic on all pages but this one).
Exceptions. Some shots are taken by other means and are added manually or using loadnew.php.

260202-151937 / Hogan The R2c graph.
260202-110112 / 26-1301 Feb 2 H13: G-Sets (6).
260202-105334 / 26-1301 Feb 2 H13: G-Sets (5).
260202-104558 / 26-1301 Feb 2 H13: G-Sets (4).
260202-103440 / 26-1301 Feb 2 H13: G-Sets (3).
260202-102133 / 26-1301 Feb 2 H13: G-Sets (2).
260202-101024 / 26-1301 Feb 2 H13: G-Sets.
260130-164839 / Murugesan Carving width (3).
260130-164838 / Murugesan Carving width (2).
260130-155316 / Enriquez CYBE to QYBE, also with C's, 2026 version (4).
260130-144932 / 25-347 The structure theorem of modules: Towards uniqueness (9).
260130-144931 / 25-347 The structure theorem of modules: Towards uniqueness (8).
260130-144930 / 25-347 The structure theorem of modules: Towards uniqueness (7).
260130-144929 / 25-347 The structure theorem of modules: Towards uniqueness (6).
260130-144928 / 25-347 The structure theorem of modules: Towards uniqueness (5).
260130-144927 / 25-347 The structure theorem of modules: Towards uniqueness (4).
260130-144926 / 25-347 The structure theorem of modules: Towards uniqueness (3).
260130-144925 / 25-347 The structure theorem of modules: Towards uniqueness (2).
260130-144924 / 25-347 The structure theorem of modules: Towards uniqueness.
260128-161105 / 25-347 The structure theorem of modules: examples, PIDs (24).
260128-161104 / 25-347 The structure theorem of modules: examples, PIDs (23).
260128-161103 / 25-347 The structure theorem of modules: examples, PIDs (22).
260128-161102 / 25-347 The structure theorem of modules: examples, PIDs (21).
260128-161101 / 25-347 The structure theorem of modules: examples, PIDs (20).
260128-161100 / 25-347 The structure theorem of modules: examples, PIDs (19).
260128-161059 / 25-347 The structure theorem of modules: examples, PIDs (18).
260128-161058 / 25-347 The structure theorem of modules: examples, PIDs (17).
260128-161057 / 25-347 The structure theorem of modules: examples, PIDs (16).
260128-161056 / 25-347 The structure theorem of modules: examples, PIDs (15).
260128-161055 / 25-347 The structure theorem of modules: examples, PIDs (14).
260128-161054 / 25-347 The structure theorem of modules: examples, PIDs (13).
260128-161053 / 25-347 The structure theorem of modules: examples, PIDs (12).
Date-Time / Prefix Comment
260128-161052 / 25-347 The structure theorem of modules: examples, PIDs (11).
260128-161050 / 25-347 The structure theorem of modules: examples, PIDs (10).
260128-161049 / 25-347 The structure theorem of modules: examples, PIDs (9).
260128-161048 / 25-347 The structure theorem of modules: examples, PIDs (8).
260128-161047 / 25-347 The structure theorem of modules: examples, PIDs (7).
260128-161046 / 25-347 The structure theorem of modules: examples, PIDs (6).
260128-161045 / 25-347 The structure theorem of modules: examples, PIDs (5).
260128-161044 / 25-347 The structure theorem of modules: examples, PIDs (4).
260128-161043 / 25-347 The structure theorem of modules: examples, PIDs (3).
260128-161042 / 25-347 The structure theorem of modules: examples, PIDs (2).
260128-161041 / 25-347 The structure theorem of modules: examples, PIDs.
260127-180153 / 26-1301 Jan 27 H11-12: Coverings, tilings, categories (13).
260127-175951 / 26-1301 Jan 27 H11-12: Coverings, tilings, categories (12).
260127-175938 / 26-1301 Jan 27 H11-12: Coverings, tilings, categories (11).
260127-174208 / 26-1301 Jan 27 H11-12: Coverings, tilings, categories (10).
260127-173032 / 26-1301 Jan 27 H11-12: Coverings, tilings, categories (9).
260127-172409 / 26-1301 Jan 27 H11-12: Coverings, tilings, categories (8).
260127-171757 / 26-1301 Jan 27 H11-12: Coverings, tilings, categories (7).
260127-165820 / 26-1301 Jan 27 H11-12: Coverings, tilings, categories (6).
260127-165609 / 26-1301 Jan 27 H11-12: Coverings, tilings, categories (5).
260127-165034 / 26-1301 Jan 27 H11-12: Coverings, tilings, categories (4).
260127-164639 / 26-1301 Jan 27 H11-12: Coverings, tilings, categories (3).
260127-163501 / 26-1301 Jan 27 H11-12: Coverings, tilings, categories (2).
260127-160702 / 26-1301 Jan 27 H11-12: Coverings, tilings, categories.
260126-110130 / 26-1301 Jan 26 H10: Half class on coverings (2).
260126-110129 / 26-1301 Jan 26 H10: Half class on coverings.
260123-152457 / 25-347 Jacob on the "ring" of modules (9).
260123-152456 / 25-347 Jacob on the "ring" of modules (8).
260123-152455 / 25-347 Jacob on the "ring" of modules (7).
260123-152454 / 25-347 Jacob on the "ring" of modules (6).
260123-152453 / 25-347 Jacob on the "ring" of modules (5).
260123-152452 / 25-347 Jacob on the "ring" of modules (4).
Date-Time / Prefix Comment
260123-152451 / 25-347 Jacob on the "ring" of modules (3).
260123-152450 / 25-347 Jacob on the "ring" of modules (2).
260123-152449 / 25-347 Jacob on the "ring" of modules.
260121-145750 / 25-347 Matt on tensor products (18).
260121-145749 / 25-347 Matt on tensor products (17).
260121-145748 / 25-347 Matt on tensor products (16).
260121-145747 / 25-347 Matt on tensor products (15).
260121-145746 / 25-347 Matt on tensor products (14).
260121-145745 / 25-347 Matt on tensor products (13).
260121-145744 / 25-347 Matt on tensor products (12).
260121-145743 / 25-347 Matt on tensor products (11).
260121-145742 / 25-347 Matt on tensor products (10).
260121-145741 / 25-347 Matt on tensor products (9).
260121-145740 / 25-347 Matt on tensor products (8).
260121-145739 / 25-347 Matt on tensor products (7).
260121-145738 / 25-347 Matt on tensor products (6).
260121-145737 / 25-347 Matt on tensor products (5).
260121-145736 / 25-347 Matt on tensor products (4).
260121-145735 / 25-347 Matt on tensor products (3).
260121-145734 / 25-347 Matt on tensor products (2).
260121-145733 / 25-347 Matt on tensor products.
260120-175640 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (22).
260120-175331 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (21).
260120-174606 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (20).
260120-173954 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (19).
260120-173621 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (18).
260120-173315 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (17).
260120-172434 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (16).
260120-172317 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (15).
260120-172204 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (14).
260120-170154 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (13).
260120-170123 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (12).
Date-Time / Prefix Comment
260120-164637 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (11).
260120-164527 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (10).
260120-164236 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (9).
260120-164127 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (8).
260120-163555 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (7).
260120-163233 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (6).
260120-162737 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (5).
260120-162529 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (4).
260120-162150 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (3).
260120-161855 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II (2).
260120-161817 / 26-1301 Jan 20 H8-9: Kupers on Seifert van Kampen II.
260119-110258 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen (15).
260119-110249 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen (14).
260119-105330 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen (13).
260119-105123 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen (12).
260119-105119 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen (11).
260119-104346 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen (10).
260119-104342 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen (9).
260119-104048 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen (8).
260119-103055 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen (7).
260119-102652 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen (6).
260119-102341 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen (5).
260119-101850 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen (4).
260119-101614 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen (3).
260119-101609 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen (2).
260119-101603 / 26-1301 Jan 19 H7: Kupers on Seifert van Kampen.
260119-101443 / Enriquez CYBE to QYBE, also with C's, 2026 version (3).
260119-101442 / Enriquez CYBE to QYBE, also with C's, 2026 version (2).
260119-101441 / Enriquez CYBE to QYBE, also with C's, 2026 version.
260116-142518 / 25-347 gcd and lcm, the structure theorem (8).
260116-142517 / 25-347 gcd and lcm, the structure theorem (7).
260116-142516 / 25-347 gcd and lcm, the structure theorem (6).
Date-Time / Prefix Comment
260116-142515 / 25-347 gcd and lcm, the structure theorem (5).
260116-142514 / 25-347 gcd and lcm, the structure theorem (4).
260116-142513 / 25-347 gcd and lcm, the structure theorem (3).
260116-142512 / 25-347 gcd and lcm, the structure theorem (2).
260116-142511 / 25-347 gcd and lcm, the structure theorem.
260114-123519 / 25-347 The Euclidean algorithm, modules (20).
260114-123518 / 25-347 The Euclidean algorithm, modules (19).
260114-123517 / 25-347 The Euclidean algorithm, modules (18).
260114-123516 / 25-347 The Euclidean algorithm, modules (17).
260114-123515 / 25-347 The Euclidean algorithm, modules (16).
260114-123514 / 25-347 The Euclidean algorithm, modules (15).
260114-123513 / 25-347 The Euclidean algorithm, modules (14).
260114-123512 / 25-347 The Euclidean algorithm, modules (13).
260114-123511 / 25-347 The Euclidean algorithm, modules (12).
260114-123510 / 25-347 The Euclidean algorithm, modules (11).
260114-123509 / 25-347 The Euclidean algorithm, modules (10).
260114-123508 / 25-347 The Euclidean algorithm, modules (9).
260114-123507 / 25-347 The Euclidean algorithm, modules (8).
260114-123506 / 25-347 The Euclidean algorithm, modules (7).
260114-123505 / 25-347 The Euclidean algorithm, modules (6).
260114-123504 / 25-347 The Euclidean algorithm, modules (5).
260114-123503 / 25-347 The Euclidean algorithm, modules (4).
260114-123502 / 25-347 The Euclidean algorithm, modules (3).
260114-123501 / 25-347 The Euclidean algorithm, modules (2).
260114-123500 / 25-347 The Euclidean algorithm, modules.
260113-180323 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (17).
260113-175720 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (16).
260113-175712 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (15).
260113-175104 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (14).
260113-174343 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (13).
260113-174340 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (12).
260113-174331 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (11).
Date-Time / Prefix Comment
260113-172156 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (10).
260113-172144 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (9).
260113-170256 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (8).
260113-170242 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (7).
260113-164944 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (6).
260113-164423 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (5).
260113-163551 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (4).
260113-163205 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (3).
260113-162238 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications (2).
260113-161241 / 26-1301 Jan 13 H5-6: Functoriallity, topological applications.
260112-170306 / Martchenkov $\rho_1$ and stir fry.
260112-142635 / SantosK Understanding the Alexander module (2).
260112-110126 / 26-1301 The fundamental theorem of algebra, categories (10).
260112-105907 / 26-1301 The fundamental theorem of algebra, categories (9).
260112-105558 / 26-1301 The fundamental theorem of algebra, categories (8).
260112-104837 / 26-1301 The fundamental theorem of algebra, categories (7).
260112-104726 / 26-1301 The fundamental theorem of algebra, categories (6).
260112-104321 / 26-1301 The fundamental theorem of algebra, categories (5).
260112-103850 / 26-1301 The fundamental theorem of algebra, categories (4).
260112-103843 / 26-1301 The fundamental theorem of algebra, categories (3).
260112-103218 / 26-1301 The fundamental theorem of algebra, categories (2).
260112-102047 / 26-1301 The fundamental theorem of algebra, categories.
260109-132328 / 25-347 Odds and ends on UFDs, PIDs, and GCDs (8).
260109-132327 / 25-347 Odds and ends on UFDs, PIDs, and GCDs (7).
260109-132326 / 25-347 Odds and ends on UFDs, PIDs, and GCDs (6).
260109-132325 / 25-347 Odds and ends on UFDs, PIDs, and GCDs (5).
260109-132324 / 25-347 Odds and ends on UFDs, PIDs, and GCDs (4).
260109-132323 / 25-347 Odds and ends on UFDs, PIDs, and GCDs (3).
260109-132322 / 25-347 Odds and ends on UFDs, PIDs, and GCDs (2).
260109-132321 / 25-347 Odds and ends on UFDs, PIDs, and GCDs.
260107-164547 / Murugesan Carving width.
260107-123558 / 25-347 Jan 7 H37-38: Rings with similar properties to Z (7).
Date-Time / Prefix Comment
260107-123557 / 25-347 Jan 7 H37-38: Rings with similar properties to Z (6).
260107-123556 / 25-347 Jan 7 H37-38: Rings with similar properties to Z (5).
260107-123555 / 25-347 Jan 7 H37-38: Rings with similar properties to Z (4).
260107-123554 / 25-347 Jan 7 H37-38: Rings with similar properties to Z (3).
260107-123553 / 25-347 Jan 7 H37-38: Rings with similar properties to Z (2).
260107-123552 / 25-347 Jan 7 H37-38: Rings with similar properties to Z.
260106-180333 / 26-1301 $\pi_1(S^1)$ (12).
260106-180325 / 26-1301 $\pi_1(S^1)$ (11).
260106-175333 / 26-1301 $\pi_1(S^1)$ (10).
260106-175327 / 26-1301 $\pi_1(S^1)$ (9).
260106-172446 / 26-1301 $\pi_1(S^1)$ (8).
260106-172433 / 26-1301 $\pi_1(S^1)$ (7).
260106-165555 / 26-1301 $\pi_1(S^1)$ (6).
260106-164930 / 26-1301 $\pi_1(S^1)$ (5).
260106-163954 / 26-1301 $\pi_1(S^1)$ (4).
260106-163930 / 26-1301 $\pi_1(S^1)$ (3).
260106-163901 / 26-1301 $\pi_1(S^1)$ (2).
260106-162115 / 26-1301 $\pi_1(S^1)$.
260105-110227 / 26-1301 Course introduction, the fundamental group (7).
260105-105354 / 26-1301 Course introduction, the fundamental group (6).
260105-104543 / 26-1301 Course introduction, the fundamental group (5).
260105-103750 / 26-1301 Course introduction, the fundamental group (4).
260105-103744 / 26-1301 Course introduction, the fundamental group (3).
260105-101956 / 26-1301 Course introduction, the fundamental group (2).
260105-100731 / 26-1301 Course introduction, the fundamental group.
251218-110657 / Martchenkov Cars and Seifert.
251217-041211 / VanDerVeen Various Seifert thoughts.
251202-114242 / Hogan Not a pentagon!
251202-114241 / VanDerVeen Tanglifying Seifert surfaces.
251128-123912 / 25-347 Nov 28 H36: primes and irreducibles (9).
251128-123911 / 25-347 Nov 28 H36: primes and irreducibles (8).
251128-123910 / 25-347 Nov 28 H36: primes and irreducibles (7).
Date-Time / Prefix Comment
251128-123909 / 25-347 Nov 28 H36: primes and irreducibles (6).
251128-123908 / 25-347 Nov 28 H36: primes and irreducibles (5).
251128-123907 / 25-347 Nov 28 H36: primes and irreducibles (4).
251128-123906 / 25-347 Nov 28 H36: primes and irreducibles (3).
251128-123905 / 25-347 Nov 28 H36: primes and irreducibles (2).
251128-123904 / 25-347 Nov 28 H36: primes and irreducibles.
251127-130002 / Martchenkov Comparing Wirtinger and Seifert.
251127-110357 / Hogan Seifert cycles and boundaries.
251126-130900 / 25-347 Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (13).
251126-130859 / 25-347 Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (12).
251126-130858 / 25-347 Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (11).
251126-130857 / 25-347 Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (10).
251126-130856 / 25-347 Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (9).
251126-130855 / 25-347 Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (8).
251126-130854 / 25-347 Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (7).
251126-130853 / 25-347 Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (6).
251126-130852 / 25-347 Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (5).
251126-130851 / 25-347 Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (4).
251126-130850 / 25-347 Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (3).
251126-130849 / 25-347 Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (2).
251126-130848 / 25-347 Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals.
251124-115443 / Hogan The OTL graph is connected.
251121-134449 / 25-347 Nov 21 H33: Quotients, iso theorems, fields (7).
251121-134448 / 25-347 Nov 21 H33: Quotients, iso theorems, fields (6).
251121-134447 / 25-347 Nov 21 H33: Quotients, iso theorems, fields (5).
251121-134446 / 25-347 Nov 21 H33: Quotients, iso theorems, fields (4).
251121-134445 / 25-347 Nov 21 H33: Quotients, iso theorems, fields (3).
251121-134444 / 25-347 Nov 21 H33: Quotients, iso theorems, fields (2).
251121-134443 / 25-347 Nov 21 H33: Quotients, iso theorems, fields.
251120-131100 / Martchenkov The co-Dehn presentation.
251119-170142 / 25-347 Nov 19 H31-32: Morphisms of rings, Cayley-Hamilton, ideals, quotients (12).
251119-170141 / 25-347 Nov 19 H31-32: Morphisms of rings, Cayley-Hamilton, ideals, quotients (11).

Date-Time / Prefix	Comment	What? A collection of Blackboard Shots (8598, right now, with 205 prefixes), mostly taken in my office using a ceiling-mounted web camera. Why? Mostly for my own use and for the use of the other people with whom I share blackboard space. And it is public because the easiest way to make something viewable to a number of people is to make it viewable to the whole world. Oh no! If you found your handwriting here and you don't like it, please let me know and the relevant shot(s) will be removed, no questions asked. How? A ceiling-mounted Logitech QuickCam Pro 9000 web camera is permanently pointed at my blackboard and connected via USB to this web server. The script bbs.php initiates a capture (using luvcview; hit "s" to shoot and "q" to quit), prompts for a file name prefix and a comment, and runs make. The makefile runs MakeDatabase.php (if necessary) to update the ShotDatabase.php. The latter file is used by index.php, which is this page, and also by show.php, used to display individual shots. The makefile also updates bbs.zip, which contains all the above mentioned scripts as well as common.php, showprefix.php, loadnew.php, random.php, the JavaScript actions.js, and the icon bbs.jpg. Finally, $\TeX$-like rendering uses MathJax (automatic on all pages but this one). Exceptions. Some shots are taken by other means and are added manually or using loadnew.php.
260202-151937 / Hogan	The R2c graph.
260202-110112 / 26-1301	Feb 2 H13: G-Sets (6).
260202-105334 / 26-1301	Feb 2 H13: G-Sets (5).
260202-104558 / 26-1301	Feb 2 H13: G-Sets (4).
260202-103440 / 26-1301	Feb 2 H13: G-Sets (3).
260202-102133 / 26-1301	Feb 2 H13: G-Sets (2).
260202-101024 / 26-1301	Feb 2 H13: G-Sets.
260130-164839 / Murugesan	Carving width (3).
260130-164838 / Murugesan	Carving width (2).
260130-155316 / Enriquez	CYBE to QYBE, also with C's, 2026 version (4).
260130-144932 / 25-347	The structure theorem of modules: Towards uniqueness (9).
260130-144931 / 25-347	The structure theorem of modules: Towards uniqueness (8).
260130-144930 / 25-347	The structure theorem of modules: Towards uniqueness (7).
260130-144929 / 25-347	The structure theorem of modules: Towards uniqueness (6).
260130-144928 / 25-347	The structure theorem of modules: Towards uniqueness (5).
260130-144927 / 25-347	The structure theorem of modules: Towards uniqueness (4).
260130-144926 / 25-347	The structure theorem of modules: Towards uniqueness (3).
260130-144925 / 25-347	The structure theorem of modules: Towards uniqueness (2).
260130-144924 / 25-347	The structure theorem of modules: Towards uniqueness.
260128-161105 / 25-347	The structure theorem of modules: examples, PIDs (24).
260128-161104 / 25-347	The structure theorem of modules: examples, PIDs (23).
260128-161103 / 25-347	The structure theorem of modules: examples, PIDs (22).
260128-161102 / 25-347	The structure theorem of modules: examples, PIDs (21).
260128-161101 / 25-347	The structure theorem of modules: examples, PIDs (20).
260128-161100 / 25-347	The structure theorem of modules: examples, PIDs (19).
260128-161059 / 25-347	The structure theorem of modules: examples, PIDs (18).
260128-161058 / 25-347	The structure theorem of modules: examples, PIDs (17).
260128-161057 / 25-347	The structure theorem of modules: examples, PIDs (16).
260128-161056 / 25-347	The structure theorem of modules: examples, PIDs (15).
260128-161055 / 25-347	The structure theorem of modules: examples, PIDs (14).
260128-161054 / 25-347	The structure theorem of modules: examples, PIDs (13).
260128-161053 / 25-347	The structure theorem of modules: examples, PIDs (12).
Date-Time / Prefix	Comment
260128-161052 / 25-347	The structure theorem of modules: examples, PIDs (11).
260128-161050 / 25-347	The structure theorem of modules: examples, PIDs (10).
260128-161049 / 25-347	The structure theorem of modules: examples, PIDs (9).
260128-161048 / 25-347	The structure theorem of modules: examples, PIDs (8).
260128-161047 / 25-347	The structure theorem of modules: examples, PIDs (7).
260128-161046 / 25-347	The structure theorem of modules: examples, PIDs (6).
260128-161045 / 25-347	The structure theorem of modules: examples, PIDs (5).
260128-161044 / 25-347	The structure theorem of modules: examples, PIDs (4).
260128-161043 / 25-347	The structure theorem of modules: examples, PIDs (3).
260128-161042 / 25-347	The structure theorem of modules: examples, PIDs (2).
260128-161041 / 25-347	The structure theorem of modules: examples, PIDs.
260127-180153 / 26-1301	Jan 27 H11-12: Coverings, tilings, categories (13).
260127-175951 / 26-1301	Jan 27 H11-12: Coverings, tilings, categories (12).
260127-175938 / 26-1301	Jan 27 H11-12: Coverings, tilings, categories (11).
260127-174208 / 26-1301	Jan 27 H11-12: Coverings, tilings, categories (10).
260127-173032 / 26-1301	Jan 27 H11-12: Coverings, tilings, categories (9).
260127-172409 / 26-1301	Jan 27 H11-12: Coverings, tilings, categories (8).
260127-171757 / 26-1301	Jan 27 H11-12: Coverings, tilings, categories (7).
260127-165820 / 26-1301	Jan 27 H11-12: Coverings, tilings, categories (6).
260127-165609 / 26-1301	Jan 27 H11-12: Coverings, tilings, categories (5).
260127-165034 / 26-1301	Jan 27 H11-12: Coverings, tilings, categories (4).
260127-164639 / 26-1301	Jan 27 H11-12: Coverings, tilings, categories (3).
260127-163501 / 26-1301	Jan 27 H11-12: Coverings, tilings, categories (2).
260127-160702 / 26-1301	Jan 27 H11-12: Coverings, tilings, categories.
260126-110130 / 26-1301	Jan 26 H10: Half class on coverings (2).
260126-110129 / 26-1301	Jan 26 H10: Half class on coverings.
260123-152457 / 25-347	Jacob on the "ring" of modules (9).
260123-152456 / 25-347	Jacob on the "ring" of modules (8).
260123-152455 / 25-347	Jacob on the "ring" of modules (7).
260123-152454 / 25-347	Jacob on the "ring" of modules (6).
260123-152453 / 25-347	Jacob on the "ring" of modules (5).
260123-152452 / 25-347	Jacob on the "ring" of modules (4).
Date-Time / Prefix	Comment
260123-152451 / 25-347	Jacob on the "ring" of modules (3).
260123-152450 / 25-347	Jacob on the "ring" of modules (2).
260123-152449 / 25-347	Jacob on the "ring" of modules.
260121-145750 / 25-347	Matt on tensor products (18).
260121-145749 / 25-347	Matt on tensor products (17).
260121-145748 / 25-347	Matt on tensor products (16).
260121-145747 / 25-347	Matt on tensor products (15).
260121-145746 / 25-347	Matt on tensor products (14).
260121-145745 / 25-347	Matt on tensor products (13).
260121-145744 / 25-347	Matt on tensor products (12).
260121-145743 / 25-347	Matt on tensor products (11).
260121-145742 / 25-347	Matt on tensor products (10).
260121-145741 / 25-347	Matt on tensor products (9).
260121-145740 / 25-347	Matt on tensor products (8).
260121-145739 / 25-347	Matt on tensor products (7).
260121-145738 / 25-347	Matt on tensor products (6).
260121-145737 / 25-347	Matt on tensor products (5).
260121-145736 / 25-347	Matt on tensor products (4).
260121-145735 / 25-347	Matt on tensor products (3).
260121-145734 / 25-347	Matt on tensor products (2).
260121-145733 / 25-347	Matt on tensor products.
260120-175640 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (22).
260120-175331 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (21).
260120-174606 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (20).
260120-173954 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (19).
260120-173621 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (18).
260120-173315 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (17).
260120-172434 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (16).
260120-172317 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (15).
260120-172204 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (14).
260120-170154 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (13).
260120-170123 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (12).
Date-Time / Prefix	Comment
260120-164637 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (11).
260120-164527 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (10).
260120-164236 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (9).
260120-164127 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (8).
260120-163555 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (7).
260120-163233 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (6).
260120-162737 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (5).
260120-162529 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (4).
260120-162150 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (3).
260120-161855 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II (2).
260120-161817 / 26-1301	Jan 20 H8-9: Kupers on Seifert van Kampen II.
260119-110258 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen (15).
260119-110249 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen (14).
260119-105330 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen (13).
260119-105123 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen (12).
260119-105119 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen (11).
260119-104346 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen (10).
260119-104342 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen (9).
260119-104048 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen (8).
260119-103055 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen (7).
260119-102652 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen (6).
260119-102341 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen (5).
260119-101850 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen (4).
260119-101614 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen (3).
260119-101609 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen (2).
260119-101603 / 26-1301	Jan 19 H7: Kupers on Seifert van Kampen.
260119-101443 / Enriquez	CYBE to QYBE, also with C's, 2026 version (3).
260119-101442 / Enriquez	CYBE to QYBE, also with C's, 2026 version (2).
260119-101441 / Enriquez	CYBE to QYBE, also with C's, 2026 version.
260116-142518 / 25-347	gcd and lcm, the structure theorem (8).
260116-142517 / 25-347	gcd and lcm, the structure theorem (7).
260116-142516 / 25-347	gcd and lcm, the structure theorem (6).
Date-Time / Prefix	Comment
260116-142515 / 25-347	gcd and lcm, the structure theorem (5).
260116-142514 / 25-347	gcd and lcm, the structure theorem (4).
260116-142513 / 25-347	gcd and lcm, the structure theorem (3).
260116-142512 / 25-347	gcd and lcm, the structure theorem (2).
260116-142511 / 25-347	gcd and lcm, the structure theorem.
260114-123519 / 25-347	The Euclidean algorithm, modules (20).
260114-123518 / 25-347	The Euclidean algorithm, modules (19).
260114-123517 / 25-347	The Euclidean algorithm, modules (18).
260114-123516 / 25-347	The Euclidean algorithm, modules (17).
260114-123515 / 25-347	The Euclidean algorithm, modules (16).
260114-123514 / 25-347	The Euclidean algorithm, modules (15).
260114-123513 / 25-347	The Euclidean algorithm, modules (14).
260114-123512 / 25-347	The Euclidean algorithm, modules (13).
260114-123511 / 25-347	The Euclidean algorithm, modules (12).
260114-123510 / 25-347	The Euclidean algorithm, modules (11).
260114-123509 / 25-347	The Euclidean algorithm, modules (10).
260114-123508 / 25-347	The Euclidean algorithm, modules (9).
260114-123507 / 25-347	The Euclidean algorithm, modules (8).
260114-123506 / 25-347	The Euclidean algorithm, modules (7).
260114-123505 / 25-347	The Euclidean algorithm, modules (6).
260114-123504 / 25-347	The Euclidean algorithm, modules (5).
260114-123503 / 25-347	The Euclidean algorithm, modules (4).
260114-123502 / 25-347	The Euclidean algorithm, modules (3).
260114-123501 / 25-347	The Euclidean algorithm, modules (2).
260114-123500 / 25-347	The Euclidean algorithm, modules.
260113-180323 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (17).
260113-175720 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (16).
260113-175712 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (15).
260113-175104 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (14).
260113-174343 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (13).
260113-174340 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (12).
260113-174331 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (11).
Date-Time / Prefix	Comment
260113-172156 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (10).
260113-172144 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (9).
260113-170256 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (8).
260113-170242 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (7).
260113-164944 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (6).
260113-164423 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (5).
260113-163551 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (4).
260113-163205 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (3).
260113-162238 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications (2).
260113-161241 / 26-1301	Jan 13 H5-6: Functoriallity, topological applications.
260112-170306 / Martchenkov	$\rho_1$ and stir fry.
260112-142635 / SantosK	Understanding the Alexander module (2).
260112-110126 / 26-1301	The fundamental theorem of algebra, categories (10).
260112-105907 / 26-1301	The fundamental theorem of algebra, categories (9).
260112-105558 / 26-1301	The fundamental theorem of algebra, categories (8).
260112-104837 / 26-1301	The fundamental theorem of algebra, categories (7).
260112-104726 / 26-1301	The fundamental theorem of algebra, categories (6).
260112-104321 / 26-1301	The fundamental theorem of algebra, categories (5).
260112-103850 / 26-1301	The fundamental theorem of algebra, categories (4).
260112-103843 / 26-1301	The fundamental theorem of algebra, categories (3).
260112-103218 / 26-1301	The fundamental theorem of algebra, categories (2).
260112-102047 / 26-1301	The fundamental theorem of algebra, categories.
260109-132328 / 25-347	Odds and ends on UFDs, PIDs, and GCDs (8).
260109-132327 / 25-347	Odds and ends on UFDs, PIDs, and GCDs (7).
260109-132326 / 25-347	Odds and ends on UFDs, PIDs, and GCDs (6).
260109-132325 / 25-347	Odds and ends on UFDs, PIDs, and GCDs (5).
260109-132324 / 25-347	Odds and ends on UFDs, PIDs, and GCDs (4).
260109-132323 / 25-347	Odds and ends on UFDs, PIDs, and GCDs (3).
260109-132322 / 25-347	Odds and ends on UFDs, PIDs, and GCDs (2).
260109-132321 / 25-347	Odds and ends on UFDs, PIDs, and GCDs.
260107-164547 / Murugesan	Carving width.
260107-123558 / 25-347	Jan 7 H37-38: Rings with similar properties to Z (7).
Date-Time / Prefix	Comment
260107-123557 / 25-347	Jan 7 H37-38: Rings with similar properties to Z (6).
260107-123556 / 25-347	Jan 7 H37-38: Rings with similar properties to Z (5).
260107-123555 / 25-347	Jan 7 H37-38: Rings with similar properties to Z (4).
260107-123554 / 25-347	Jan 7 H37-38: Rings with similar properties to Z (3).
260107-123553 / 25-347	Jan 7 H37-38: Rings with similar properties to Z (2).
260107-123552 / 25-347	Jan 7 H37-38: Rings with similar properties to Z.
260106-180333 / 26-1301	$\pi_1(S^1)$ (12).
260106-180325 / 26-1301	$\pi_1(S^1)$ (11).
260106-175333 / 26-1301	$\pi_1(S^1)$ (10).
260106-175327 / 26-1301	$\pi_1(S^1)$ (9).
260106-172446 / 26-1301	$\pi_1(S^1)$ (8).
260106-172433 / 26-1301	$\pi_1(S^1)$ (7).
260106-165555 / 26-1301	$\pi_1(S^1)$ (6).
260106-164930 / 26-1301	$\pi_1(S^1)$ (5).
260106-163954 / 26-1301	$\pi_1(S^1)$ (4).
260106-163930 / 26-1301	$\pi_1(S^1)$ (3).
260106-163901 / 26-1301	$\pi_1(S^1)$ (2).
260106-162115 / 26-1301	$\pi_1(S^1)$.
260105-110227 / 26-1301	Course introduction, the fundamental group (7).
260105-105354 / 26-1301	Course introduction, the fundamental group (6).
260105-104543 / 26-1301	Course introduction, the fundamental group (5).
260105-103750 / 26-1301	Course introduction, the fundamental group (4).
260105-103744 / 26-1301	Course introduction, the fundamental group (3).
260105-101956 / 26-1301	Course introduction, the fundamental group (2).
260105-100731 / 26-1301	Course introduction, the fundamental group.
251218-110657 / Martchenkov	Cars and Seifert.
251217-041211 / VanDerVeen	Various Seifert thoughts.
251202-114242 / Hogan	Not a pentagon!
251202-114241 / VanDerVeen	Tanglifying Seifert surfaces.
251128-123912 / 25-347	Nov 28 H36: primes and irreducibles (9).
251128-123911 / 25-347	Nov 28 H36: primes and irreducibles (8).
251128-123910 / 25-347	Nov 28 H36: primes and irreducibles (7).
Date-Time / Prefix	Comment
251128-123909 / 25-347	Nov 28 H36: primes and irreducibles (6).
251128-123908 / 25-347	Nov 28 H36: primes and irreducibles (5).
251128-123907 / 25-347	Nov 28 H36: primes and irreducibles (4).
251128-123906 / 25-347	Nov 28 H36: primes and irreducibles (3).
251128-123905 / 25-347	Nov 28 H36: primes and irreducibles (2).
251128-123904 / 25-347	Nov 28 H36: primes and irreducibles.
251127-130002 / Martchenkov	Comparing Wirtinger and Seifert.
251127-110357 / Hogan	Seifert cycles and boundaries.
251126-130900 / 25-347	Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (13).
251126-130859 / 25-347	Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (12).
251126-130858 / 25-347	Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (11).
251126-130857 / 25-347	Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (10).
251126-130856 / 25-347	Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (9).
251126-130855 / 25-347	Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (8).
251126-130854 / 25-347	Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (7).
251126-130853 / 25-347	Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (6).
251126-130852 / 25-347	Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (5).
251126-130851 / 25-347	Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (4).
251126-130850 / 25-347	Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (3).
251126-130849 / 25-347	Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals (2).
251126-130848 / 25-347	Nov 26 H34-35: Fields and maximal ideals, domains and prime ideals.
251124-115443 / Hogan	The OTL graph is connected.
251121-134449 / 25-347	Nov 21 H33: Quotients, iso theorems, fields (7).
251121-134448 / 25-347	Nov 21 H33: Quotients, iso theorems, fields (6).
251121-134447 / 25-347	Nov 21 H33: Quotients, iso theorems, fields (5).
251121-134446 / 25-347	Nov 21 H33: Quotients, iso theorems, fields (4).
251121-134445 / 25-347	Nov 21 H33: Quotients, iso theorems, fields (3).
251121-134444 / 25-347	Nov 21 H33: Quotients, iso theorems, fields (2).
251121-134443 / 25-347	Nov 21 H33: Quotients, iso theorems, fields.
251120-131100 / Martchenkov	The co-Dehn presentation.
251119-170142 / 25-347	Nov 19 H31-32: Morphisms of rings, Cayley-Hamilton, ideals, quotients (12).
251119-170141 / 25-347	Nov 19 H31-32: Morphisms of rings, Cayley-Hamilton, ideals, quotients (11).

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