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A glance at the academic work of Professor Chung-Tao Yang

Professor Chung-Tao Yang published an impressive list of mathematical works most of
which are in topology, more precisely, manifolds with group action. Among his mathematical
works, the most influential is the one on the Blaschke conjecture—together with others, he
solved affirmatively the sphere version of the conjecture. To our knowledge, the following is
a summary of Professor Yang’s work, and we refer the interested readers to his publication
for more details.

(I) In his early age, Professor Yang was interested in finite projective geometry, and published
some impressive work, in particular that on finite geometry of spheres, projective plane and
projective collineation.

(II) From 1950’s and on, Professor Yang, alone or together with Dean Montgomery et al.,
published some influential work on transformation group, in particular that on group action
on spheres. In that baby age of algebraic topology and differential topology, these results are
ground-breaking and hence lay the foundation of the theory thereof.

(III) From 1980’s and on, Professor Yang applied the technique of transformation group to
study the Blaschke conjecture and came up with his affirmative solution to the conjecture in
the sphere case.

(IV) As well-known in the mathematics community, Hilbert’s 23 problems in 1900 play a
leading role in the development of mathematics in the 20th century. As a leading mathematician
in his field, Professor Yang was among very few distinguished mathematicians chosen to
present the status of Hilbert’s problems in the Hilbert symposium organized by the American
Mathematical Society in 1974.

Being both a productive researcher and an enthusiastic educator in mathematics, Professor
Chung-Tao Yang came back to Taiwan from time to time to give lectures and to advise us in
all aspects of mathematics. The Institute of Mathematics, Academia Sinica is saddened to lose
such a good teacher.