Wednesday, February 22, 2012

Happy 80th Birthday, Rufus!

RogerSquires A very happy birthday to Roger Squires aka Rufus/Dante, one of the best-loved crossword setters in the world. There's a nice profile of him up on the Guardian blog today, a special cryptic crossword by Enigmatist in the Guardian [25565] and many glowing tributes written for him on fifteensquared. Do check them out.

And if you haven't yet, read Roger's interview on Crossword Unclued – the most visited post on my blog in 2011.

Here's a selection of 10 superbly crafted clues by the inimitable setter. Enjoy solving.

1. News rooms (8) Q_______

2. Well-fed, he is round in form (9) N_______

3. Loaf around for a while? (5,5) S____ ____D

4. Physical training instructor (6) M_____

5. Still to come or already gone? (4) L___

6. Father is up and about (4) S___

7. Asian playing solitaire, but not having to? (7) I______

8. Gay Lib - the organisation (6) B_____

9. Lincoln died sleeping? Apparently so (4) A___

10. Out of sight, out of mind (5,3,4) R____ ___ ___D

Update: More birthday posts for Roger Squires – a special puzzle on Big Dave's blog and an interview by Alan Connor.

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Friday, February 17, 2012

15 Crossword Tweeters You Should Know About

twitter#followfriday is a twitter tradition of suggesting interesting people to follow on twitter. Posting a long version of it on my blog this Friday. I hope this inspires some of you who aren't on twitter, to now become a part of it.

Before I joined twitter, I thought of it as a place where celebrities made controversial remarks and the rest wrote mundane details of their personal lives. I thought it wasn't for me. It is only after joining that I've realised this: like on the rest of the web, twitter is what you want it to be. I tweet about crosswords, follow people whose tweets relate to my interests, and absolutely love it. Twitter introduced me to many crossword enthusiasts I might not have known otherwise. Thanks to Tony for getting me to join.

My recommendations for twitter accounts of crossword-related people.

Crossword Setters, Editors

image @anaxcrosswords Dean Mayer aka Anax/Loroso/Elkamere. Cryptic crossword setter for The Times, Independent, Telegraph, FT and Sunday Times.
image @BoatmanCryptics Ashley aka Boatman. Guardian crossword setter.
image @crypticpaul John Halpern. Crossword setter for The Guardian, Financial Times, The Times & The Independent.
image @diogeneb Crossword setter for The Hindu (Textrous) and Mint.
image @eimi_indy Mike Hutchinson. Crossword editor of The Independent, for which he also sets as Eimi.
image @Mickhodgkin  Mick Hodgkin aka crossword setter Morph/Micawber.
image @notytony Tony Sebastian. Crossword setter for The Hindu (Cryptonyte) and Mint.
image @obel David Tossman. Crossword setter for the New Zealand Listener.
image @Will_Shortz Will Shortz. Crossword editor, The New York Times.

For cryptic clues on twitter:

image @aclueaday Clues by a crossword setter from Newport.
image @sancryptic Clues by hobbyist setter Sanjeev Vaidyanathan.

Crossword Bloggers, Webmasters

image @alanconnor Alan Connor. Blogger on the Guardian Crossword blog.
image @dzharrison Derek Harrison of The Crossword Centre.
image @mhl20 Mark Longair. Blogger on Fifteensquared.
image @tilsit Dave Tilley. Blogger on Big Dave's Crossword blog.

Crossword Super Solvers

A growing list of crossword enthusiasts who participate in twitter conversations about cryptic crosswords and solve cryptic clues with amazing speed. Follow the list: Crossword Super Solvers.

Know of crossword tweeters not listed here? You're welcome to add your suggestions in the comments.

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Monday, February 13, 2012

The notorious A on B device

a-on-b-cryptic-clues The proper use of "on" in cryptic clues has been a matter of long-standing debate/confusion in crossword circles. Is "A on B" equal to AB (A before B), or is it BA (A after B)? Can it mean either, or only one of the two?

The dictionary definition of "on" provides several possible interpretations. Since "on" means "next to", it can be reasoned that "A on B" implies adjacent in any direction. The issue then is of fairness to the solver. Does allowing any possible interpretation of "on" make the clue too tough? Or, as with "about", can solvers handle the word's many meanings?

The last I heard, the Times crossword allowed "A on B" to mean only one thing – BA in Across clues, AB in Down clues [check out this discussion on UKPuzzle]. As the examples below show, not all publications adhere to this convention.


In the Times crossword, you will not see "A on B" = AB in in Across clues. Others seem open to this interpretation.

Independent 7887 (Crosophile): Not prepared to be sent over to remote place on earth for conflict (7) WARFARE
RAW (not prepared) reversed, FAR (remote place) on i.e. adjacent to E (Earth)

FT 13448 (Jason) Wager on group providing storage space? (8) BACKPACK
BACK (wager) on i.e. adjacent to PACK (group)

THC 10383 (Textrous): Practical joke on a loony (4) GAGA
GAG (practical joke) on i.e. adjacent to A


The most common way of treating "A on B" in Across clues – A attached to the end of B.

FT13866 (Falcon): A very bad argument on singular Mayfair street (6,3) SAVILE ROW
A VILE (very bad) ROW (argument) on i.e. after S (singular)

Times 24691: Prepare to leave hotel agent with a thousand on account (6) REPACK
REP (agent), K (a thousand) on i.e. after AC (account)

DOWN: A on B = AB

A on top of B is the usual reading for "A on B" in Down clues, the opposite of its widely accepted meaning in Across clues.

FT 13587 (Dante): Upset, go on about a terrible person (4) OGRE
GO upset i.e. reversed, on i.e. on top of RE (about)

DOWN: A on B = BA

"A on B" = BA is rare in Down clues but by no means non-existent. The Across clue logic "A attached to the end of B" can hold equally good for Down clues.

FT 13587 (Dante): Arrives, riding on a posh car (5,2) ROLLS UP
UP (riding) on i.e. after ROLLS (posh car)

Interestingly, the Down clues for OGRE and ROLLS UP, with their different ways of treating "A on B",  appeared consecutively in the same crossword.

What do you think?

As a solver, are you OK with "A on B" meaning either AB or BA, or would you prefer a single meaning only? If you're open to either interpretation, do you expect an internal consistency within the same crossword?

If you are a setter, how do you want "A on B" to work? Do you find the restriction to a single meaning limiting/illogical?

Solve These

[Across] Indy 7897 (Punk): Holy woman on business having something of a tattoo - that's a problem (9) C_______M
[Across] Times 24790: See what’s in store with hard work on operating system (6-4) W_____-___P

[Down] Guardian 25555 (Boatman): Star puts curse on a music industry award: Boatman's lost (8) H______M
[Down] Times 25034: Drug, one injected during surgery on tummy at regular intervals (5) O____

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Tuesday, February 7, 2012

Can a computer program write cryptic clues?

I bet your answer is a vehement "No" (unless you are Spiffytrix's friend). Grid fills maybe, anagram suggestions - but entire clues? Not possible. This isn't Sudoku to get generated by software.

That's what I thought, which is why Enigma took me by surprise. Enigma, the brainchild of David Hardcastle, is a computer program that auto-generates cryptic clues for any word input. David built this program over a period of four years, as part of his thesis for PhD in Computer Science, Birkbeck, University of London.

In his thesis [p245], David says:

there is a widely held (and probably well-founded) belief that computers can generate English language but not “natural” English language. A key goal for ENIGMA is to challenge that belief, and for the system to generate clues with fluent surface texts.

How Enigma Works

Given a word, the first step is to figure out all the ways the word can be clued using the puzzle rubrics configured in the system. The user can then select a particular type from the list and generate clues using that type.

Let's see this work for the input word VIEWERS. The system comes up with a number of "clue plans".


"Exp" represents the number of possible combinations through which the clue could be expressed, where 4 means 104 =10,000 etc.

We select the fifth clue plan - (anagram(WIVES) around ER) - and click the Generate button, then the system generates clues which are shown ordered by rank.

[click to enlarge]

Enigma generates the clues by treating the clue plan as a set of chunks and generating text for one chunk at a time. For example, (WIVES)* translates to chunks of text like 'strange wives', 'wives about', 'reorder wives' etc. The system discards those chunks that don't work syntactically (e.g. 'wives problem') or don't work semantically (e.g. 'jumbled wives').

The (rather unfortunate) phrase 'battered wives' scores above other similar alternatives such as 'fancy wives' since it is matched as a "collocate" i.e. a phrase in English with these exact words. The system recognises thematic associations between words by computing word distance between pairs of words in a 100 million word corpus (the British National Corpus) and using a statistical algorithm to determine whether or not a given pair of words is unusually correlated in the text.

Next the system finds ways of representing ER, such as hospital department, pause, etc.

Then the system explores all frames representing 'A in B' with all the combinations of the 'anagram of WIVES' chunk and the 'ER' chunk to try to build a new, meaningful chunk for that whole piece of the clue.

The auto-generated explanation for this clue is:


How Good Are Enigma-Generated Clues?

When Enigma was built, David conducted an evaluation in two ways –

1. Turing-style test – For the same light, two clues were provided – an Enigma-generated clue and a Sun newspaper clue. 30 pairs of such clues were presented and solvers were asked to pick the Enigma-generated clue from each pair.

2. Domain expert assessment - Crossword compilers Jonathan Crowther and Don Manley, editors Kate Fassett and Mike Hutchison, and expert solvers provided their feedback on clue quality.

60 people participated in the Turing-style test and on average they correctly guessed the clue from the Sun newspaper 70% of the time. The best score (parity with the newspaper) was 50% and the worst (obvious to tell apart) 100%. The pairs (now marked with which is Enigma-generated) are here.

The domain experts were harsher critics of the system and found most clues lacking in human wit. The surface reading was right some of the time but not all the time. Another criticism was based on originality. For example, ENIGMA scored the clue "Drain fresh ewers (5)" for SEWERS high, however this has been used often in cryptic clues and a human setter familiar with crosswords would avoid it. While this similarity with human output is something of a success, ENIGMA's inability to recognise originality which comes to human setters is a failing.

The major drawback of Enigma is its dependency on the encoded semantics, which in its current state is rather shallow. For example, in the VIEWERS clue, a human compiler would have spotted 'without hesitation' as a construct for '… around ER', and using same elements have made "Witnesses battered wives without hesitation (7)", a much more fluent clue. This Enigma has not managed – because 'B without A' has not been encoded.

The problem gets compounded when the clue length increases, with the surface becoming nonsensical. The system has no strategic planning component to organise the surface beyond clause and sub-clause level.

Read the detailed evaluation here [p228-262].

The domain experts were asked if any of the clues of a set of 42 were of publishable quality. Mike Hutchinson highlighted 10 clues, Jonathan Crowther highlighted 8 and Sandy Balfour 9. One can conclude that, while Enigma is no threat to human crossword setters, it does get it right at least some of the time.

A Puzzle to Try

Have a go at this crossword with clues generated entirely by Enigma:

Enigma Crossword

Answers here.

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