Mauricio Kagel is a composer
who was born in Buenos Aires
on Christmas Eve
1931. Most likely if you find somebody who can name an Argentinian
composer at all, it will be Kagel (unless they think of the accordian
ist Astor Piazzola
as a composer).
Although Kagel has written some pretty traditional pieces for pretty traditional groups of instruments like string quartets and piano trios, not to mention some film music, he is better known for his more experimental work, which often makes use of the collage of other composer's music. He also frequently emphasises the theatrical element of musical performance. For instance, in his String Quartet No. 1, he asks the performers to stare at each other and look surprised (as if they have played a wrong note), and at one point he asks the first violinist to "creep up, unnoticed, behind the viola." All these actions are carefully scored, and are to be considered part of the music (like it or not, that's how Kagel sees it). Obviously, the effect of these actions is often humourous, and comedy is a big part of a lot of Kagel's work.
Another example of his experimentation is "Ludwig van." Kagel had a mock-up of Beethoven's studio made, and covered everything, walls, doors, chairs, a music stand, the piano, everything, in sheet music of Beethoven's piano sonatas. He then made a film of various shots of the interior of this room. The soundtrack was a pianist playing whatever music was visible on the screen at that time. Because the sheet music was wrapped around objects, often overlapped or was creased and folded, the result was very different to what Beethoven originally envisioned. There are still recognisable bits of Beethoven in there, however. This rethinking of old music is another major element in Kagel's work, and makes him a post-modernist (inasmuch as the term means anything at all).
Kagel's music isn't for everybody, and suffers very badly without the visual element. In this sense, Kagel is a lot like Liberace, only with less hair.