How do the notes on the treble and bass staves here correspond to each other? (Mozart K331 Mvmt 1 Var. V Measure 100)

In this measure 100 of the Variation V of Mozart's K.331, I'm trying to get it right which note on the treble staff is played at the same moment as which note on the bass staff. In the image I drew the lines of what I think is the correspondence (played at the same time), with dashed lines in doubt.

Every two quadruple beam notes together is equivalent to one triple beam note, right? So in Measure 100 (the second measure in the image), the first 8 notes on the upper staff correspond to the first 4 notes on the lower staff, right?

Then the 9~12th notes on top (BCDE) on a quadruple beam correspond to the 5~6th notes on the bottom (AF on a triple beam), right?

From the 13th note on top (F), and the 7th note on bottom (D), both staves are now triple beams, so the notes have one-to-one correspondence, correct? Are the dashed lines I drew correct? Is that the printing doesn't have the accurate positioning of the two staves' notes (the magenta line should be rather vertical)? Also, does the DF on treble correspond to the last F on the bass? or no?

• by the way, I know it makes it harder to fit to your diagram, but these are all F#s and C#s, and would be written in text as "F#", "C#", rather than "F", "C". Jul 20, 2023 at 9:56
• Mozart took the trouble to notate everything correctly here, but even if he hadn't, the obviously intended effect would "a really fast run up to the high D", and no one will much care (or notice) whether the triplet notes are really 25% slower than the preceding notes or not. Jul 20, 2023 at 11:16
• @James Martin Yes I know, I wrote the notes there just for referring convenience. Jul 20, 2023 at 19:36
• @Kilian Foth For a beginner it's important to get everything right. I'm glad I asked the question; it really helps me to learn about beats, better than just reading general theory without a context or example, and without my having a question/curiosity first. Jul 20, 2023 at 19:40

In the upper staff, the fourth group of notes is a triplet. Those three notes correspond to the lower staff's seventh and eighth notes (i.e., second grouping, second two notes).

Here, given by note number, are the correspondences.

```RH 1 3 5 7    9 11 13    16 18    20    22
LH 1 2 3 4    5  6  7     9 11    13/14 15/16
```

• Thank you Aaron! I definitely need to study the beats (been too lazy). Two questions: (1) In that triplet you mentioned (FGA), if the number "3" were not there, would it make difference? (2) Do all music scores print the notes in the exact positions they should be, as far as aligning upper and lower staves is concerned (such as where you drew the two vertical dashes above)? Or do some printing have the notes shifted away a little making it inaccurate? I guess the sure way is always to count the beats, but just wonder if the printing could also help me to reassure. Jul 20, 2023 at 2:38
• @GrandAdagio If the "3" were missing, the beaming would still make things clear. But I think what you're really asking is "what it wasn't a triplet and, instead, just three ordinary 32nd notes?" in that case, the right hand part would be one 32nd note too long, so it would be clear there was some sort of error. Jul 20, 2023 at 2:50
• @GrandAdagio In general, music engravers try to align note heads according to when that note is played, but in measure like this one with so many notes, it can be difficult to show the alignment clearly. Jul 20, 2023 at 2:52
• @GrandAdagio Yes, the triplet is a bit slower than what came before and a bit faster than what comes after. Very tricky for a beginner. Jul 20, 2023 at 2:54
• @GrandAdagio "I guess the sure way is always to count the beats": if you had done that without taking the triplet into account you would have come up with an extra thirty-second note (demisemiquaver) in the right hand because the triplet consists of three notes played in the time of two "normal" notes of the same value. In other words, if you removed the "3" without making any other changes then the notation would be incorrect. Jul 20, 2023 at 8:45