Quadratic unconstrained binary optimization

Quadratic unconstrained binary optimization (QUBO) is a pattern matching technique, common in machine learning applications. QUBO is an NP hard problem.

QUBO problems may sometimes be well-suited to algorithms aided by quantum annealing.

QUBO is the problem of minimizing a quadratic polynomial over binary variables. The quadratic polynomial will be of the form ${\displaystyle E(X_{1},X_{2},...,X_{N})=\sum _{i=1}^{N}c_{i}X_{i}+\sum _{i=1}^{N}\sum _{j=1}^{i}Q_{ij}\times X_{i}\times X_{j}}$ with ${\displaystyle X_{i}\in \{0,1\}}$ and ${\displaystyle c_{i},Q_{ij}\in R}$.

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