Cube Counting invisible cub

This forum made possible through the generous support of SDN members, donors, and sponsors. Thank you.

drillbitjoe

Full Member
10+ Year Member
Advertisement - Members don't see this ad
I came across this one today on crack PAT...so it turns out there is no cube on the ground-level row in the middle. Since it is being blocked, I assumed there was one there due to "row continuation". How can you know there isnt?
upload_2014-6-24_1-37-35.png