For every infinite loop space machine 
,
there is a natural equivalence of spectra between 
and Segal's spectrum 
.
May-Thomason Uniqueness Theorem
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References
May, J. P. and Thomason, R. W. "The Uniqueness of Infinite Loop Space Machines." Topology 17, 205-224, 1978.Weibel, C. A. "The Mathematical Enterprises of Robert Thomason." Bull. Amer. Math. Soc. 34, 1-13, 1996.Referenced on Wolfram|Alpha
May-Thomason Uniqueness TheoremCite this as:
Weisstein, Eric W. "May-Thomason Uniqueness Theorem." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/May-ThomasonUniquenessTheorem.html