It's always amusing to watch two kids who don't trust each other swap baseball cards by exchanging them at exactly the same moment. Words can be equally mistrustful about trading their letters. Watch this:
SOLVER SLIDER | | | | · · · · · · · · · · · I O · · | | | | SLIVER SOLDER | | | | · · · · · · · · · D V · · | | | | SLIDER SOLVER
Notice that with each step:
— One letter is extracted from each word, the two letters are swapped, and each letter is reinserted into the other word (but not necessarily in the same place where the other letter was extracted).
— Letters can be extracted from anywhere in the word, and can be inserted anywhere in the word. However, all the remaining letters must maintain their relative order.
— Both words must be valid English words at each step.
Now here is your challenge. Start with this pair:
and, through a series of simultaneous swaps, transform it into this pair:
The example at the top shows how powerful simultaneous swapping can be. It switches SOLVER and SLIDER in just two steps! More often, however, progress is a bit more incremental.
It can sometimes take several steps to get each letter to where it needs to go. Observe:
TRIED SLACKER | | | | · · · · · · · · · A I · · | | | | TREAD SLICKER | | | | · · · · · · · · · I A · · | | | | TIRED SLACKER
This maneuver allows the word TRIED to be anagrammed to TIRED while keeping the other word (SLACKER) fixed. It is reminiscent of how some people solve the Rubik's cube, employing a sequence of manipulations which moves one square into a desired position while keeping all the other squares fixed. Sometimes it may take multiple steps to attain this isolated movement.
If the conditions are right, you can actually anagram one of the words in a single step. You do this by extracting the same letter from each word. Watch this:
POACHED PEAR | | | | · · · · · · · · · E E · · | | | | POACHED PARE
It's an exchange of "E" for "E", changing PEAR to PARE, but effectively leaving POACHED unchanged.
And, of course, you can use this technique to anagram both words simultaneously:
EMPATHIC EARTHY | | | | · · · · · · · · · H H · · | | | | EMPHATIC HEARTY
Here is a more leisurely solution path using familiar words:
@ace — Thanks for sharing your computer-generated solutions!