also a means of computing homological invariants from the knot diagram. Towards the end of his life, Alexander became a recluse. He was known as a socialist and his prominence brought him to the attention of McCarthyists. The atmosphere of the McCarthy era pushed him into a greater seclusion. He was not seen in public after 1954, when he appeared to sign a letter supporting J. Robert Oppenheimer. Death and legacy He died on September 23, 1971. The Alexander's Chimney, in the Rocky Mountain National Park, is named after him. See also Alexander horned sphere Alexander polynomial Alexander cochain Alexander–Spanier cohomology Alexander duality Alexander's trick References Sources James, I. M., Portrait of Alexander (1888–1971), Bull. Amer. Math. Soc. (N.S.) 38 (2001), no. 2, 123–129. Cohen, Leon W., James Waddell Alexander (1888–1971), Bull. Amer. Math. Soc. 79 (1973), no. 5, 900—903. External links Author profile in the database zbMATH 1888 births 1971 deaths 20th-century American mathematicians Topologists Institute for Advanced Study faculty Princeton University faculty People from Sea Bright, New Jersey Princeton University alumni Mathematicians from New Jersey