Plagiarism In Song Assignment

The instance involving Joe Satriani's "If I Could Fly" and Coldplay's "Viva La Vida" doesn't strike me as a legitimate case of plagiarism. The notes of the lead singers voice resemble the guitar notes played in Joe Satriani's song, however, the resemblance between the two is merely that and not a complete replica. I beleive that this case is a coincidental relationship between the two songs that may have arisen from the singers subconcious mimicry of the familiar note of Joe Satriani's solo. On that note, the lead singers voice only follows one small segment of the guitar solo and not the entire thing. The song has enough variation in its vocals to make it similar yet different from Joe Satriani's song. The Red Hot Chili Peppers' song "Dani California" does appear to be a legitimate plagiarism of Tom Petty's "Mary Jane's Last Dance," however. The rhythm of both guitar parts in each of these songs is just too similar to possibly be coincidence. Not only are the two parts nearly identical but they both persist throughout a good portion of the song and are nearly trademarks of each. Just hearing the rhythm of the guitars alone brings to mind one and both of these songs at the same time.