We prove an upper bound on sums of squares of minors of {+1, −1}-matrices. The bound is sharp for Hadamard matrices, a result due to de Launey and Levin [‘(1, −1)-matrices with near-extremal properties’, SIAM J. Discrete Math. 23 (2009), 1422–1440], but our proof is simpler. We give several corollaries relevant to minors of Hadamard matrices. 2010 Mathematics subject classification: primary 05B...

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