Henri Cartan, who was known as one of the world's foremost mathematicians of the last half of the 20th century, died Aug. 13 in Paris. No cause of death was reported for Dr. Cartan, who was 104.

Almost all of Dr. Cartan's career was spent in France, and he was acclaimed for his research in pure mathematics, including algebra, topology and the analytic functions of complex variables. He was also an influential writer and teacher.

At least two of his pupils won Nobel prizes, one in economics and one in physics. Two others received the Fields Medal, which is awarded for accomplishment in mathematics and is regarded as the mathematics equivalent of the Nobel Prize. In 1980, Dr. Cartan received the Wolf Prize, also one of the highest honors in mathematics.

Among mathematicians, Dr. Cartan was remembered as the last survivor of the Bourbaki group, a kind of cabal of younger, rebellious French mathematicians who in the 1930s essentially rewrote the book on their subject. Their work extended to 36 volumes, which were carefully studied for years.

In the United States, he worked with Samuel Eilenberg, another important mathematician of the 20th century. Their 1956 book, "Homological Algebra," was regarded as a classic of mathematics and a reference for many researchers.

In an extended 1999 interview published by the American Mathematical Society, Dr. Cartan referred to his work on that treatise with wit and modesty.

"All of it was written by Sammy," Dr. Cartan said. "I wrote nothing.

"Of course we had discussions, but after that, Sammy wrote. I was in charge of correcting the spelling mistakes -- in English! I don't know much English, but I can spell."

During World War II, one of Dr. Cartan's two brothers was executed by the Nazis for his connections to the French Resistance. After the war, Dr. Cartan was known as a leading champion of European unity.

In applying reason and logic to politics, he said, he became a European federalist, recognizing that "there is no other way" than unity.

He also was known for his advocacy on behalf of mathematicians, including some in the Soviet Union, who were persecuted for their politics.

He was married for many years and had at least two children, but details about survivors could not be learned.

Dr. Cartan was born in Nancy, France, on July 8, 1904. His father, Elie Cartan, was an equally renowned mathematician.

The younger Dr. Cartan received his doctorate in 1928 from the Ecole Normale Superieure in Paris. He taught there for much of the time from 1940 to 1965.