QUESTION! More Diminished Chords.

[Vussel Riste]

So I originally learned the Diminished Chord formula as:
I-ii-Vdim-VI
Then another source tells me, its just: I-ii-Vdim.
But then the “minor chord with a flat 5 and flat 7” comes around which looks like a diminished chord with a flat 7.
I don’t know which is which, unless I’m missing something here.
Can someone explain?
Thanks!

 

[idssdi]

Basically a diminished chord is 4 minor thirds stacked upon each other. The chord formula would be 1 b3 b5 bb7. Playing these intervals together will make up a diminished chords. Than you have the half-diminised chord which has formula 1 b3 b5 b7. Be wary that a half-diminised chord can also function as a minor 6 chord(i.e. B half-diminished is the same as Dm6).
Also I have a question about your notation. As far as my knowledge goes Roman numerals are used to show harmony. So they show a chord progression and don’t function as a chord formula. Vdim really means the V chord is a diminished chord in your progression(which seems pretty weird for me since the V chord is a dominant chord)

 

[Vussel Riste]

According to the books I use:
-The Roman Numerals provide a shorthand notation to talk about all 12 notes in the Western 12-tone scale.
-Its a relative system of notation: The I or root can be any note.
-The capitalized Roman Numerals are the notes in the Major Scale.
-The other 5 notes have Roman numbers and names that describe their relative location.

 

[Vussel Riste]

Unless that was completely wrong and I’ve been memorizing false knowledge for months now.

 

[idssdi]

Roman numerals really are chords. That’s why an uppercase is major and a lowercase is minor. A note on his own has no such thing as a minor note or a major note because what makes a note minor or major is it’s relation to another note(i.e. minor and major thirds etc.)
https://study.com/academy/lesson/roman-numeral-notation-in-music-theory.html

 

[Vussel Riste]

Either way, I’d love to know everybody else’s way of notation, It’ll make it easier for me to communicate with you guys.

 

[idssdi]

I’m not trying to diss you or anything. Just making sure you get the right information

 

[Vussel Riste]

No, its cool. Like I said, I wanna learn everybody else’s way of notation so its easier for me to communicate with the rest of you guys.

 

[Vussel Riste]

And I’m actually glad you told me because I really don’t want to be stuck with false info.