for assisting me with my explorations of LDS history. Thanks also to Charles Doriean and Nathan Kalmoe for discussions and practical assistance with this paper. Thanks to Anna Grzymala‐Busse, Rob Mickey, Jennet Kirkpatrick and Ken Kollman for comments on earlier versions of this paper.

Abstract Based on simple combinatorial arguments, we formulate a generalized cavity method where the Random Overlap Structure (ROSt) probability space of Aizenmann, Sims and Starr is obtained in constructive way, use it to give simplified derivation Parisi formula for free energy Sherrington–Kirkpatrick model.