Abraham Robinson

Others such as Wilhelmus Luxemburg showed that the same results could be achieved using ultrafilters which made Robinson's work more accessible to mathematicians who lacked training in formal logic. I Model theory and algebra Yale University Press ISBN 978-0-300-02071-7 MR 533887 
Robinson Abraham (1979) in Luxemburg W. Robinson was strongly interested in the history and philosophy of mathematics and often remarked that he wanted to get inside the head of Leibniz the first mathematician to attempt to articulate clearly the concept of infinitesimal numbers.

Abraham Robinson (born Robinsohn; October 6 1918 – April 11 1974) was a mathematician who is most widely known for development of non-standard analysis a mathematically rigorous system whereby infinitesimal and infinite numbers were incorporated into mathematics.