Passage: In 1940, Friedman accepted a position at the University of Wisconsin<unk>Madison, but left because of differences with faculty regarding United States involvement in World War II. Friedman believed the United States should enter the war. In 1943, Friedman joined the Division of War Research at Columbia University (headed by W. Allen Wallis and Harold Hotelling), where he spent the rest of World War II working as a mathematical statistician, focusing on problems of weapons design, military tactics, and metallurgical experiments. In 1945, Friedman submitted Incomes from Independent Professional Practice (co-authored with Kuznets and completed during 1940) to Columbia as his doctoral dissertation. The university awarded him a PhD in 1946. Friedman spent the 1945<unk>1946 academic year teaching at the University of Minnesota (where his friend George Stigler was employed). On February 12, 1945, his son, David D. Friedman was born. Question: What year was Friedman's son born?
1945 <unk>