These instances are complete graphs with euclidian distances. They were converted by Ralf Borndörfer and Carlos Ferreira from TSPLIB problems, by selecting some nodes as Terminals.
berlin52 is made out of 52 sights in Berlin.
brazil58 are 58 cities in Brazil with the provincial capitals as terminals.
world666 are 666 cities around the world with the capitals as terminals.
More information can be found among others in KM98 and PD00 .
The files can be found in the download section.
The column DC classifies the difficulty of the instance.
The letter after class gives an impression how long it takes to solve the problem using state-of-the-art soft- and hardware. secounds means less than a minute (this includes instances which can be solved in fractions of a second). minutes means less than an hour. hours is less than a day and days is less than a week. weeks mean it takes really a long time to solve this instance. ? means the instance is not solved or the time is not known.
If the number in the Opt column is written in italics the optimum is not known. The number given is the best know upper bound.