Well, the way it's written, it kind of is... :)

Not the easiest code to read at all.

Interesting. Thanks for the insight.

"&&" is preferred over "and" as a logical operator in Ruby, "and" can lead to unexpected behavior in some cases.

Here's an answer I wrote up on Quora about it: Why don't many programmers use the keywords "or" and "and" in their programs but always opt for "||" and “&&"?.

Out of curiosity, how long do new kata typically stay in Beta? Is more than a year pretty standard?

This is by far the hardest 6kyu I've completed. Most 5's and even some 4's that I've solved are easier. Is there any consideration for regrading this Kata?

Agreed. I was even thinking a 4, most 5's are easier than this one.

It says to sort them in alphabetical order in the case of ties.

In the ruby version, the closing parenthesis is in the wrong place in the tests, giving a "wrong number of arguments" error by default

It should look like this: Test.assert_equals(elements_sum([[3, 2, 1, 0], [4, 6, 5, 3, 2], [9, 8, 7, 4]], 16))

But instead, the tests look like this: Test.assert_equals(elements_sum([[3, 2, 1, 0], [4, 6, 5, 3, 2], [9, 8, 7, 4]]), 16), so the 'd' value is never passed in as an argument.

Is this the only recursive solution?