Thursday, April 15, 2021

Tuesday, April 13, 2021

Tuesday ASMR

 Haven't posted an ASMR video for awhile, so without further adieu...:



Thursday, April 8, 2021

Classic....

 You are hopefully familiar with knight/knave logic problems (made famous by Raymond Smullyan) — knights are truthtellers who always tell the truth, while knaves always lie. The following is a nice, interesting one (in which Leon & Larry are liars, and Tim a truthteller), originally from Smullyan, but quoted in Jason Rosenhouse’s current volume “Games For Your Mind”:


You meet triplets named Leon, Larry, and Tim. They are visibly indistinguishable, but Leon and Larry are knaves, while Tim is a knight… What one question  could you direct to one of the brothers to determine whether or not he is Larry?


answer below:

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ANSWER:

Suppose you simply randomly ask one of the brothers, “Are you Larry?” This does no good. Both Tim and Larry will say “no,” and Leon will say “yes.” A yes answer would identify Leon, but a no answer could come from either Tim or Larry, and fails to ID which is which.

If instead we ask, “Are you Tim?” then everyone will simply respond “yes” and we gain nothing. 

The intriguing part is that if we ask, “Are you Leon?” the responder will give away whether he is or is not Larry. Larry will lie and answer “yes.” Tim will tell the truth and say “no,” and Leon will lie, also saying “no.” We know anyone answering “no” is not Larry, and anyone replying “yes” must be Larry.



Tuesday, April 6, 2021

Puzzle This!

                                                                 987654321

Interesting Twitter thread (h/t to Keith Devlin for pointing to it) on "decreasing" and "increasing" numbers:

https://twitter.com/Laurie_Rubel/status/1379024067123154945


Sunday, April 4, 2021

For the More Advanced and Insightful Readers of This Blog....

 Apologies for being a few days late in posting this (H/T to Colm Mulcahy for pointing to it):


If you find this video too difficult to wrap your brain around you may want to wait and bone up a bit by first reading a basic topology text, or perhaps alternatively, Jordan Ellenberg's latest upcoming volume "Shape."


Tuesday, March 30, 2021

Put On Your Thinking Caps

Just fun stuff this morning, starting with two puzzles adapted from a recent edition of AARP Magazine (which somehow found its way into my hands ;)

1)  Every six-digit integer which is made up of repeated pairs of three-digit numbers, like 573,573, 831,831, or 107,107, is evenly divisible by the same four-digit integer. What is that integer?


2)  and a less mathy, word puzzle:


Look over the following 7 verbs. Taken together they share a specific, unusual trait. What is it?


bring

buy

catch

fight

seek

teach

think


(…I’m usually fairly good with word puzzles, but this one stumped me)


ANSWERS at bottom of post.


…and lastly, from Twitter this recent post:

https://twitter.com/PhDemetri/status/1376692648753397766


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ANSWERS:  1)  1001

            2)  the past tense of all these verbs rhyme, even though none of the present tenses do

                       (brought, bought, caught, fought, sought, taught, thought)



Monday, March 29, 2021

"Lethal Force"... The Escalation of Antiscience

 Antiscience has emerged as a dominant and highly lethal force, and one that threatens global security, as much as do terrorism and nuclear proliferation….

The full antiscience agenda of the Republican Party has now gone beyond our national borders. In the summer of 2020, the language of the antiscience political right in America was front and center at antimask and antivaccine rallies in Berlin, London and Paris.”

Not strictly math at all, but Scientific American piece on the “anti-science” movement (largely of the Republican Party) as the politically, societally, security threat that it is:


https://www.scientificamerican.com/article/the-antiscience-movement-is-escalating-going-global-and-killing-thousands/



Wednesday, March 24, 2021

Statistical Practices — the Bad Driving Out the Good

 H/T to Mike Lawler for pointing out this essay (and “belly-aching”) from Darren Dahly on common statistical (mal)practice, particularly in medicine:

https://statsepi.substack.com/p/how-bad-statistical-practices-drive


Too many great sentences in this (about the author's slog against research "bullshit") I’d love to quote, but will simply give you the opening lines:

I am interested in research integrity and reproducibility. I believe that a lack of statistical expertise throughout the sciences is a substantial driver of problems in these areas (poor data practices being another). I feel especially strongly about this thesis as it applies to medical research.”    — Darren Dahly



Friday, March 19, 2021

The Partisanship of Vaccine Reluctance

 

Andrew Gelman explores a bit of the possible sharp dichotomy (as well as confounding variables) in Republican versus Democrat reluctance to receive the Covid vaccine:

https://statmodeling.stat.columbia.edu/2021/03/18/huge-partisan-differences-in-who-wants-to-get-vaccinated/


  The prospect of Republicans dying off at a far greater rate than Democrats (if such a dichotomy exists) due to their own skepticism/negligence, may cause some to recollect Melania's sentiments... but the prospect of Republican intransigence possibly gumming up the medical system for everyone else (and prolonging the pandemic), by their lack of involvement is concerning.



Wednesday, March 17, 2021

Sunday, March 14, 2021

Jason Rosenhouse



Recently bought Jason Rosenhouse’s Games For Your Mind The History and Future of Logic Puzzles,” his 2020 volume on, well, the history and future of logic puzzles. Just scanning through it’s pages I can tell it is a delightful compendium of puzzle and logic topics, certainly including many familiar classics, but also with material I think most readers will find new to them. On top of that I have always enjoyed Rosenhouse’s writing (indeed I’m surprised he isn’t a bit better known in the popular and recreational math writing arena). His “The Monty Hall Problem” is a fabulous treatment of that popular puzzle, and he did a similarly wonderful full volume on Sudoku, as well as co-editing other volumes on recreational math, and editing a great tribute to Raymond Smullyan.

https://tinyurl.com/yz9cs9go



Many who are familiar with Rosenhouse first became aware of him though through his former “Evolution Blog” at the old Science Blogs site. That blog title became a bit of a misnomer after he ventured into all manner of topics, having started off focusing on the evolutionist/creationist wars. His writing was always crisp and incisive whether covering math, puzzles, chess, education, politics, or culture, in addition to the original evolution theme (which he also authored a book about). Even when I disagreed with his viewpoint I always admired his logical step-by-step commentary and argumentation, and highly recommend, if you're not already familiar with him, get so, with this current Princeton University Press volume likely a great place to start.




Friday, March 12, 2021