This introduction to Cassandra Replication and Consistency (slides 14-15) boldly asserts:

R+W>N guarantees overlap of read and write quorums.

Please imagine this inequality has huge fangs, dripping with the blood of innocent, enterprise developers so you can best appreciate the terror it inspires.

I understand having the sum of the read and write Consistency Levels (R+W) greater than Replication Factor (N) is a good idea... but what's the big deal?

What are the implications, and how does R+W>N compare to the alternatives?

• R+W < N
• R+W = N
• R+W >> N