An r × n Latin Rectangle [LR] based on 1, …, n is a 2-dimensional array of r rows and n columns, where r < n, such that each entry is one of the integers 1, …, n and each of these integers occurs at most once in each row and at most once in each column.
Is it true that every r × n LR can be extended to an n × n LR (a Latin square [LS])? Why or why not?
Okay so my way of checking this is to first see what conditions need to be met that would make a LR unable to conform to a LS.
I will be making an assumption that the only case we need to worry about is the case where r = n-1 because that is the most confined example. And to convert every other example where r < n-1 to a LS is just a series of steps more trivial than the final step of the r=n-1 case.