Bouzouki Asia Minor and the subsequent exchange of populations between Greece and Turkey when the ethnic Greeks fled to Greece. The early bouzoukia were mostly three-string ("trichordo"), with three courses (six strings in three pairs) and were tuned in different ways, as to the scale one wanted to play. At the end of the 1950s, four-course (tetrachordo) bouzoukia started to gain popularity. The four-course bouzouki was made popular by Manolis Chiotis, who also used a tuning akin to standard guitar tuning, which made it easier for guitarists to play bouzouki, even as it angered purists. However it allowed for greater virtuosity
Shannon capacity of a graph eight neighbors, the eight strings that it can be confused with. A subset of length-two strings forms a code with no possible confusion if and only if it corresponds to an independent set of this graph. The set of code words {"11", "23", "35", "54", "42"} forms one of these independent sets, of maximum size. If "G" is a graph representing the signals and confusable pairs of a channel, then the graph representing the length-two codewords and their confusable pairs is "G" ⊠ "G", where the symbol "⊠" represents the strong product of graphs. This is a graph that has