His argument was incomplete , and this is ( as of 2016 ) still a major open problem .
In 1969 Alfred Adler published a paper in the American Journal of Mathematics claiming that the 6 - sphere has no complex structure .
Alfred Adler 's argument was incomplete , and this is ( as of 2016 ) still a major open problem .
In 1969 Alfred Adler published a paper in the American Journal of Mathematics claiming that the 6 - sphere has no complex structure .