 In 1960 , Stockhausen returned to the composition of vocal music ( for the first time since Gesang der Jünglinge ) with Carré for four orchestras and four choirs ( Stockhausen @-@ Verlag 2010 , 18 ) . Two years later , he began an expansive cantata titled Momente ( 1962 – 64 / 69 ) , for solo soprano , four choir groups and thirteen instrumentalists ( Stockhausen @-@ Verlag 2010 , 18 ) . In 1963 , Stockhausen created Plus @-@ Minus , " 2 × 7 pages for realisation " containing basic note materials and a complex system of transformations to which those materials are to be subjected in order to produce an unlimited number of different compositions ( Stockhausen @-@ Verlag 2010 , 20 ; Toop 2005 , 175 – 78 ) . Through the rest of the 1960s , he continued to explore such possibilities of " process composition " in works for live performance , such as Prozession ( 1967 ) , Kurzwellen , and Spiral ( both 1968 ) , culminating in the verbally described " intuitive music " compositions of Aus den sieben Tagen ( 1968 ) and Für kommende Zeiten ( 1968 – 70 ) ( Fritsch 1979 ; Kohl 1981 , 192 – 93 , 227 – 51 ; Kohl 1998b , 7 ; ( Toop 2005 , 191 – 92 ) ) . Some of his later works , such as Ylem ( 1972 ) and the first three parts of Herbstmusik ( 1974 ) , also fall under this rubric ( Maconie 2005 , 254 , 366 – 68 ) . Several of these process compositions were featured in the all @-@ day programmes presented at Expo 70 , for which Stockhausen composed two more similar pieces , Pole for two players , and Expo for three ( Kohl 1981 , 192 – 93 ; Maconie 2005 , 323 – 24 ) . In other compositions , such as Stop for orchestra ( 1965 ) , Adieu for wind quintet ( 1966 ) , and the Dr. K Sextett , which was written in 1968 – 69 in honour of Alfred Kalmus of Universal Edition , he presented his performers with more restricted improvisational possibilities ( Maconie 2005 , 262 , 267 – 68 , 319 – 20 ) . 
