On February 27, 1994, I heard Will Shortz on National Public Radio announce the winner of a contest to form the longest possible (5,4) word chain using words from Webster's 10th Collegiate. A Tulane professor came up with the eight-step SCAP-CRAPE-RAPES-APEST-PESTO-ESTOP-STOPE-TOPER-OPERA (which can be represented in compressed form as SCRAPESTOPERA).
"A (5,4) Word Chain Network,"
Word Ways: Vol. 27
, Article 20.
Available at: http://digitalcommons.butler.edu/wordways/vol27/iss2/20