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B: Draws Cab (Reader Comments)

15 July 1997

(Last updated: 1 September 1997)

Arthur supplies this switchback ladder:

  1. MIRED
  2. DENIM
  3. LINED
  4. DEVIL
  5. LIVER
  6. REVEL
  7. LEVEL
  8. LEVER
  9. BEVEL

There are several other places you can go from LEVER, such as REBEL or RAVEL, but none of them seem to lead anywhere useful. I thought it would be really cool to mirror the ladder through the palindrome—that is, to go from LEVEL back to LEVER, back to REVIL and so on through reversals of the first several steps. Unfortunately, most of those reversals (like REVIL) aren't actually words. Anyone want to produce a palindromic switchback ladder of this sort?

Dominus did a computerized search (using a program of his own devising) and came up with some very cool long switchback pairs, including three seven-letter ones:

Here are the six-letter switchbacks on his list (arbitrarily leaving out proper names (except Brazil, which I liked too much to drop) and words I've never heard of):

Dominus' list inspired me to do some searching with my own program (which does work, but it's slow and clunky and should not be used on a system with other users, since it hogs resources). With its help, I found two switchback loops (the second derived loosely from Arthur's ladder above):

later <—> fetal <—> latex <—> metal/petal <—> later

revel <—> leper <—> rebel <—> lever <—> bevel <—> levee <—> level <—> revel

The program also helped me find two long ladders, related to the loops. The first matches Arthur's nine-step ladder:

  1. sepal
  2. lapel
  3. legal
  4. lager
  5. renal
  6. later
  7. fetal
  8. latex
  9. metal

The second extends Arthur's ladder to twelve steps:

  1. mired
  2. denim
  3. lined
  4. devil
  5. liver
  6. revel
  7. leper
  8. rebel
  9. lever
  10. bevel
  11. levee
  12. level

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