How can one build a chord made of 2 notes an octave apart from more basic chords, inversions, and deletions? E.g: a chord made of C-C.
For example, one can smoothen a V7 chord by omitting the 5th and moving the 3rd and 7th down an octave, and to rephrase my question, is it possible to arrive at a chord made of a 1st and an 8th with such transformation?
If not, does that chord have a name? And how does one uses it within a progression?
Technically, the pair of notes is not a chord, it is an interval.
> A chord, in music, is any harmonic set of three or more notes that is > heard as if sounding simultaneously.
https://en.wikipedia.org/wiki/Chord_(music)
So you are talking about two notes an octave apart, that is - an perfect octave interval
see https://en.wikipedia.org/wiki/Interval_(music)#Main_intervals for more interval names
A chord by definition is a set of notes. It's why the number of each note in each chord does not affect the name of the chord. For example a C major chord contains the notes C, E, and G and you can have them in any order and any number. For example If you played the notes E2, E3, C4, G5, and C5, you would still have a C major chord. It would be in first inversion, but this only slightly changes the chord symbol and not what we cal the chord.
In your case, the only note we have in our set is C. This does not work as a chord obviously because we only have one note. Just considering major chords, this C could be part of a C major chord, A♭ major chord, and an F major chord.
