Task: Question Answering
Input (English): Passage: In 1932, after six year's teaching at the Royal College, Moore took up a post as the Head of the Department of Sculpture at the Chelsea School of Art. Artistically, Moore, Hepworth and other members of The Seven and Five Society would develop steadily more abstract work, partly influenced by their frequent trips to Paris and their contact with leading progressive artists, notably Pablo Picasso, Georges Braque, Jean Arp and Alberto Giacometti. Moore flirted with Surrealism, joining Paul Nash's modern art movement "Unit One", in 1933. In 1934, Moore visited Spain; he visited the cave of Altamira (which he described as the "Royal Academy of Cave Painting"), Madrid, Toledo and Pamplona.Moore and Nash were on the organising committee of the International Surrealist Exhibition, which took place in London in 1936. In 1937, Roland Penrose purchased an abstract 'Mother and Child' in stone from Moore that he displayed in the front garden of his house in Hampstead. The work proved controversial with other residents and the local press ran a campaign against the piece over the next two years. At this time Moore gradually transitioned from direct carving to casting in bronze, modelling preliminary maquettes in clay or plaster rather than making preparatory drawings.
In 1938, Moore met Kenneth Clark for the first time. From this time, Clark became an unlikely but influential champion of Moore's work, and through his position as member of the Arts Council of Great Britain he secured exhibitions and commissions for the artist. 
Question: What were the last names of the leading progressive artists The Seven and Five Society would contact?
Output (English): Arp.