# What is an R-complete Word™?

If a word conforms to a special rule, I call it an R-complete Word™.

Use the examples below to find the rule.

R-complete Words™ Not R-complete Words™
TAX TRIBUTE
NEEDLE PIN
SUN MOON
BEST WORST
PUZZLE RIDDLE
COFFEE TEA
SCIENCE PHILOSOPHY
COLUMN ROW
CARTOONS* SERIES
HEAVEN HELL
TRUCK LORRY

* This is a Double R-complete Word™

CSV Version:

R-complete Words™,Not R-complete Words™
TAX,TRIBUTE
NEEDLE,PIN
SUN,MOON
BEST,WORST
PUZZLE,RIDDLE
COFFEE,TEA
SCIENCE,PHILOSOPHY
COLUMN,ROW
CARTOONS*,SERIES
HEAVEN,HELL
TRUCK,LORRY


What is the rule?
There are many more R-complete Words™

Hints: A hint will be given every 50 views for the first three hints. After that, 1 hint every 100 views or 15 votes.

Hint #1 (50 views):

- It is also called 3R word because it is based on a 3-component score (Bonus: "Truck" is R-Complete and "Lorry" is not)

Hint #2 (100 views):

The R-score is defined as $$R = (R_1, R_2, R_3)$$ and a word is R-complete if $$\min(R) > 0$$

Hint #3 (150 views):

- Here is a hint in the form of mini-puzzle
- Bonus: Answering @rand-althor question, Yes, an anagram of the word will keep its property, it's still a 3-complete word.

Hint #4 (250 views):

More examples:
- R-Complete, Not R-Complete
- Ant, Bee
- Bull, Cow
- Camera, Picture
- Double, Triple

• An 3R Word or an R-complete Word? Aug 27, 2019 at 13:16
• It's a synonym, like "Truck" and "Lorry". BTW, one of these words is R-complete ;) Aug 27, 2019 at 13:55
• Hi @gustavovelascoh, welcome to PSE! Props for adding the comment hints to the puzzle itself! Since this site has solvers in many different time zones, it's considered polite to wait until the next day before adding hints, so that everyone has had a chance to see the puzzle before any crucial hints are added. Happy puzzling!
– Bass
Aug 27, 2019 at 23:53
• Would an anagram of an R-complete word still be R-complete? Aug 28, 2019 at 8:30
• @Randal'Thor I think the answer will be part of the next hint ;) Aug 28, 2019 at 11:39

I think an R-complete word is one which:

Uses letters from all 3 rows on a standard QWERTY keyboard.

In each of the counter-examples above:

There is at least one row of the keyboard which is not used.

If we:

Label letters from each row as (T)op, (M)iddle or (B)ottom and count up how many of each are used in a word then you can produce the 3-part 'R-score', R(T,M,B) like so:

TAX = TMB = R(1,1,1)
NEEDLE = BTTMMT = R(3,2,1)
SUN = MTB = R(1,1,1)
BEST = BTMT = R(2,1,1)
PUZZLE = TTBBMT = R(3,1,2)
COFFEE = BTMMTT = R(3,2,1)
SCIENCE = MBTTBBT = R(3,1,3)
COLUMN = BTMTBB = R(2,1,3)
CARTOONS = BMTTTTBM = R(4,2,2)
HEAVEN = MTMBTB = R(2,2,2)
TRUCK = TTTBM = R(3,1,1)

As per the second hint, you can see that:

The minimum value in brackets in each of these is 1 or more.

In contrast, for the counterexamples:

TRIBUTE, PIN and MOON have no letters from the middle row,
WORST, RIDDLE, TEA, PHILOSOPHY, SERIES, HELL and LORRY have no letters from the bottom row,
ROW has no letters from the middle or bottom rows.

Hence, each of these will contain a '0' somewhere in their R(T,M,B) triplet, making min(R)=0 and ensuring these words are not 'R-complete'.

The 'R' in R-complete most probably stands for:

ROWS

• You got it! Just before giving the 3rd hint. Just curious, was enough the question without hints or any of the first two was useful? Aug 28, 2019 at 13:20
• @gustavovelascoh To be honest, neither of those hints helped me crack it particularly - it just sort of fell into place at last after typing out the words! I found them more an extension of the puzzle (and that's fine), but once I had worked out the answer I was able to see how they fitted in and they make perfect sense :)
– Stiv
Aug 28, 2019 at 13:26