Originally Posted By: Tangmo
1 : a sweet or agreeable succession or arrangement of sounds.
2 : a rhythmic succession of single tones organized as an aesthetic whole a hummable melody

Legally, there is no necessity that a melody be "sweet" or "agreeable", nor must it be "hummable".

And the second definition defines a melody as being a... "melody", which isn't much of a definition.

If you're arguing that a melody "infringes":
Originally Posted By: Buzzfeed
Copyright infringement is what's called a "strict liability tort," which means the defendant doesn't have to have intended to infringe to be found guilty. To prove guilt, the plaintiff must only demonstrate that the defendant had access to the allegedly infringed song, and that the two songs in question have substantial similarity.

Demonstrating "access" is simple.

As to "substantial similarity":
Originally Posted By: Buzzfeed
Substantial similarity is a question of whether or not the average listener can tell that one song has been copied from the other. This is the "ordinary observer test," what Fakler calls "the hallmark of copyright infringement." The more elements two works have in common, the more likely they are to be ruled substantially similar. Proving substantial similarity in music cases is complicated by the fact that all songs carry two kinds of copyright, for composition and sound recording, that have to be evaluated independently.

The standard isn't that the songs "sound similar", but that "the average listener can tell that one song has been copied from the other."

Once an "average listener" is shown what elements to look for, they would be able to tell that one was "copied from the other". As an inexact copy, it would be considered a derived work:
Originally Posted By: Wikipedia
In copyright law, a derivative work is an expressive creation that includes major copyrightable elements of an original, previously created first work (the underlying work). The derivative work becomes a second, separate work independent in form from the first. The transformation, modification or adaptation of the work must be substantial and bear its author's personality sufficiently to be original and thus protected by copyright. Translations, cinematic adaptations and musical arrangements are common types of derivative works.

Originally Posted By: Tangmo
If you did not write the melody for your piece, then who did?

From a legal perspective, the question is whether the ownership of the derivative work remains with the author the work was derived from.

And the law says: yes, it does.

Originally Posted By: Tangmo
Is your melody substantially similar to the melody recognized from the Lennon-McCartney song?

Is it recognizable as having been copied from the Lennon-McCartney song?

I'd bet a jury would say yes.

Originally Posted By: Tangmo
Is it copied? Again, such elements that may be similar to the Lennon-McCartney song are not by definition melody at all.

Actually, they are "by definition" melody.

There is a legal loophole here, though. The "fair use doctrine" allows the use of copyrighted material if the resulting work is "transformative":

Originally Posted By: Wikipedia
For copyright protection to attach to a later, allegedly derivative work, it must display some originality of its own. It cannot be a rote, uncreative variation on the earlier, underlying work. The latter work must contain sufficient new expression, over and above that embodied in the earlier work for the latter work to satisfy copyright law's requirement of originality.

So it is actually transformative, or is it just a "rote process?"

By definition, exact melodic inversion is a "rote, uncreative variation" (to borrow the term), as anyone performing exact melodic inversion correctly will arrive at the same result.

Originally Posted By: Tangmo
Does the prosecution wish to claim that the lengths of melodic notes were created by his clients who now owns them for life plus 70 years? Henceforth is nobody allowed to use the same sequence of note durations as he/they did?

I'll let someone better versed in law answer that.

Per Music as a Matter of Law:

Originally Posted By: Music as a Matter of Law
Recent (and significantly less scrutinized) district court decisions have held that copyright protection could extend to a piece's rhythm, percussion, or instrumental riffs. The Sixth Circuit has upheld an infringement verdict based on copying vocal refrains of a particular rhythm and timbre. Dicta from the Ninth Circuit likewise suggest that one could infringe a musical work by copying some permutation of "chord progression, key, tempo, rhythm, and genre."

Originally Posted By: Tangmo
Since the Mssrs Lennon and/or McCartney did not and cannot claim to have written the melody, any portion of the melody, or any "melodious" (by definition) aspect of your piece, the arguments of the Plaintiff are unsupported and unsupportable. Ipso facto, corpus delecti.

McCartney and Lennon do claim to have written the melody from which the inverted melody is derived via a "rote, uncreative variation", which makes it derivative of their copyright work, and therefore, under their copyright.

-- David Cuny
My virtual singer development blog

Vocal control, you say. Never heard of it. Is that some kind of ProTools thing?