All comparisons and swaps in the code you quoted are made between adjacent elements. It's local in a way that behaves very nicely for an external sort on a tape

All comparisons and swaps in the code you quoted are made between adjacent elements. It's local in a way that behaves very nicely for an external sort on a tape drive. The code in the paper compares and swaps non-adjacent elements nearly every time. It is absolutely horrible for an external sort on a tape drive. It's just not a bubble sort, nor is it sort of like one in any key behavioral detail.