Is there a formal name for this type of composition?

Question

So, say there's a musical piece that has the following structure:

[A.1] [A.2] [A.3] [A]

Where A is a "harmonic theme", in the sense that it's treated as a theme, but its melodic content is contained in the chords' voices instead of being played by a solo instrument.

A.1-3 Are all intended as "movements", each of them being a variation of (or, inheriting from) A.

Note: I call "alien" whatever musical content wasn't directly derived from the mother A

Instrumentation

Note: Sorry for my lack of terminology.

It's basically an orchestra composed primarily of:

• Strings section
• 2 pianos (1 of which is "prepared", as in John Cage)
• Couple of cymbals
• There are also sound effects and other nontraditional or "modern" instruments (in the context of an orchestra).

The structure

This is the big picture structure of the piece:

A.1

• It's about 3:30 minutes in length
• Inherits from A
• There is a solo instrument playing a melody clearly standing out from the rest of the orchestra.
• It introduces an alien progression (compatible tonality-wise) before giving way to A.2

A.2

• It's about 5:00 minutes in length
• Inherits from A
• It simply presents its two variations of the main theme.
• The same solo instrument appears briefly.

A.3

• It's about 6:00 minutes in length
• Inherits from A
• It plays its variation twice, first as a pizzicato strings + piano, then as staccato strings + piano
• It introduces an alien progression (incompatible tonally) which has one string group playing staccatto and another playing pizzicato, and there are tritones here and there, with an almost bartokian (ha, I wish!) feeling to it, which ends in a single note which happends to be the minor 7th of the main theme's root.

A

• It's about 2:00 minutes long
• It starts with an instrumental/sonic (there are sound effects in this piece) explosion which is also the first chord of the main theme

It's important to note that the "climax" (last part where the "mother" theme is presented) ends up sounding really primitive/simple, I suppose as a result of having spent lots more brain energy when working on its children.

So, my question would be:

What is the formal term (I've been told it could be called a Fugue) that would most accurately describe this structure?

Or, a more general (and useful) way to ask the question would be: What do you call a structure that presents a main subject at the tail of a piece, after several variations of it have occurred?

Answer 1

This sounds like a Variations and Theme case. You have three variations before you come out with your theme. A more common, yet similar, form is Theme and Variations. This form is just as it sounds, the theme is stated first. Next, it is restated, but slightly altered or with different accompaniment. This is a modified strophic form basically. A strophic form is were the theme is constantly repeated, however there is no variation on it.

Theme and Variations form- Wikipedia

...'Theme and variation' forms are however based specifically on melodic variation, in which the fundamental musical idea, or theme, is repeated in altered form or accompanied in a different manner. 'Theme and variation' structure generally begins with a theme (which is itself sometimes preceded by an introduction), typically between eight and thirty-two bars in length; each variation, particularly in music of the eighteenth century and earlier, will be of the same length and structure as the theme.

Variations and Theme is not far from Theme and Variation and will employ many of the same techniques. It is, after all, only a modified version of the form. This term should accurately label the form you described in the question.