Terry Tao has put the lines below as the masthead picture of his blog. He and over 700 mathematicians (as of Tuesday 31st) have signed this petition against Trump’s “executive order” against immigration, including figures like Maryam Mirzakhani, Karen Smith, Peter Sarnak, Dana Scott, Curtis T. McMullen, Edward Witten, Efim Zelmanov, Richard Taylor, and Pierre Deligne:https://notoimmigrationban.com/.

The Mathematical Association of America and the American Mathematical Society have both officially denounced the ban.