51动漫

All dogs go to gate 97, please

EDINBURGH airport boasts a sign stating firmly: 鈥淣o dogs except guide dogs and dogs travelling with passengers.鈥� It includes a helpful ideogram of a dog crossed through in a red circle. Stephen Hoddell notes that it forbids only dogs travelling on their own which have 鈥渟uccessfully negotiated the airline ticket check, airport security and passport control鈥� before reaching the sign.

The odds on those dogs reaching the sign being able to understand it are therefore higher than for, say, dogs seeing a sign on a street (17 March 2012). So it does, Stephen says, 鈥渟eem a bit churlish to then stop them from boarding their flights鈥�.

A headline on announces: 鈥�.鈥� Like Amanda Reid, we wonder: how do they know?

Phone not a friend

OUTSIDE a coastguard hut in Cornwall, Chris Searle spotted a telephone beneath a sign reading: 鈥淓mergency phone 999 only鈥�. It might be tough to call the main UK emergency number there: the phone has just three buttons, labelled 鈥�1鈥�, 鈥�2鈥� and 鈥�3鈥�. Chris observes that the solution is 鈥渆asy 鈥� when you realise you need to tap in the number 999 in base 4, as 33213鈥�. Alternatively, you could try the European standard: 112. Either way: no one should go into the water unless they have a Feedback reader standing watch.

Train sign strain

SOME readers regret Feedback stubbornly failing to see what the writers of strange signs intended. Some regret our showing too much sympathy for them. Jim Grozier recalls how complicated the job of a sign-writing committee can be, when done properly.

An innovative information system at Brighton station in the 1980s aimed to tell passengers which train would arrive soonest at certain destinations. 鈥淔astest train鈥� wouldn鈥檛 do: the fastest might not leave for hours. 鈥淣ext fastest train鈥� was rejected, for implying 鈥渟econd fastest鈥�. Finally, 鈥渟ome genius came up with 鈥楩irst train to arrive at鈥�,鈥� and won the day. But now 鈥淣ext fastest train鈥漣s appearing on privatised UK railways. Is it, Jim wonders, perpetrated by people with very logical minds who think everyone else has very logical minds, or 鈥渂y someone who didn鈥檛 think at all鈥�?

Fear, uncertainty and doubt

WHAT is it about economists and spreadsheet embarrassment? Last year, we mentioned PhD student Thomas Herndon finding beginners鈥� mistakes in a paper that was widely used to justify austerity policies (25 May 2013).

Last month saw a ding-dong battle in the larger newspapers over Thomas Piketty鈥檚 economics bestseller Capital in the Twenty-First Century. Piketty says that inequality is increasing and calls for measures, including taxes on wealth holdings, that strike at the heart of free-market fundamentalism.

We presume that Financial Times economics editor Chris Giles sought purely to establish the statistical truth when he . 鈥淪ome issues concern sourcing and definitional problems,鈥� he said on 23 May; 鈥淪ome numbers appear simply to be constructed out of thin air.鈥� Piketty mounted a . The discourse then moved on to the subtleties of how to combine disparate data series 鈥� a problem that is familiar to climate history researchers.

Which makes Feedback muse: was Giles aware that his sowing the seed of doubt about research would be used in mimickry of what the tobacco industry did on smoking and the carbon industry is doing on climate change?

Student horticulture, yet

FEEDBACK regrets being unable to attend this year鈥檚 in London. A colleague forwards an excited announcing that the National Union of Students was exhibiting there.

The colleague 鈥渇inds this tie-up a horrible culture shock. If anyone had told me 40 years ago that it would come to this鈥� Come back, Stalinist students, all is forgiven!鈥� The NUS stand publicised a programme that 鈥渉elps students to create low-carbon, organic growing sites on their campuses鈥�, called 鈥淪tudent Eats鈥�. We amused ourselves imagining a Pot Noodle garden; then remembered seeing actual student horticulture, involving unofficial pharmaceuticals.

An inflatable economy

OFFICIAL estimates for the UK鈥檚 gross national income will henceforth include such illicit horticulture as mentioned above, and prostitution, the Office of National Statistics . Feedback now wonders what other activities a finance minister desperate to report economic growth might want to add to the list. Suggestions on a postcard, please.

Seeking measures of noneness

FINALLY, a 51动漫 leader said 鈥淚ncreasingly, none of us 鈥榙o God鈥�.鈥� (3 May, p 3). Derek White asks whether 鈥渋n the new maths there are varying levels of 鈥榥oneness鈥�?鈥� We wondered what mathematicians might call such an enumeration of non-existence. The context led us to look up 鈥渋neffable numbers鈥�.

We found that in 1991 on the old-school Usenet News group sci.math Todd Moody defined these as 鈥渢he real numbers that cannot be individually named by any finite string of symbols in any language鈥�.

We leave the question of whether the number of such numbers is none, some or infinite as an exercise for the interested reader.