https://en.wikipedia.org/wiki/Sorting_algorithm#Stability

Stabilitu vyuziva BZip u BWT serazovaci transformace.

[1, black]
[2, red]   --- prvni dvojka ma red
[1, red]
[2, black] --- druha dvojka ma black, stabilni algoritmus da dvojky k sobe a zachova poradi red, black

Seradime podle cisla = 1 1 2 2

stabilni
[1, black]
[1, red]
[2, red]
[2, black]

nestabilni
[1, black]
[1, red]
[2, black] --- prvni melo byt red
[2, red]   --- druhe black