This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

Hayek had a long-standing and close friendship with philosopher of science Karl Popper, also from Vienna. In a letter to Hayek in 1944, Popper stated, "I think I have learnt more from you than from any other living thinker, except perhaps Alfred Tarski." (See Hacohen, 2000). Popper dedicated his Conjectures and Refutations to Hayek. For his part, Hayek dedicated a collection of papers, Studies in Philosophy, Politics, and Economics, to Popper and, in 1982, said that "ever since his Logik der Forschung first came out in 1934, I have been a complete adherent to his general theory of methodology". Popper also participated in the inaugural meeting of the Mont Pelerin Society. Their friendship and mutual admiration, however, do not change the fact that there are important differences between their ideas.
Which fellow Vienna native was Hayek friends with?