A very brief summary of the event, from Internationale Situationniste #1 (June 1958)
Translated by Reuben Keehan. From: https://www.cddc.vt.edu/sionline/si/second.html
The second conference of the Situationist International met in Paris on the 25 and 26 January, six months after the founding conference of Cosio d'Arroscia in July 1957, concerned particularly with the development of our action in Northern Europe and Germany, editorial activity, the organization of a dérive by several groups in radio contact, and preliminary positions on the application of certain ambient constructions.
The conference proceeded with the purging of the Italian section, in which a faction had developed, first maintaining idealist and reactionary theses which were refuted and condemned by the majority, and then abstaining from all self-criticism. The conference thereby decided on the exclusion of Walter Olmo, Piero Simondo and Edna Verrone.