| pos(char, sortedchars) ≤ pos(char2, sortedchars) ⊦ char = char2, char < char2 |
⊦ char1 < char2 ↔ pos(char1, sortedchars) < pos(char2, sortedchars)
pos(char, sortedchars) ≤ pos(char2, sortedchars) ⊦ char = char2, pos(char, sortedchars) < pos(char2, sortedchars)
Used terms: char2, char