arXiv:2610.41678
Solving the MAX-$k$-CUT problem for hypergraphs with quantum computing
V. S. Yarmus, Kh. P. Gnatenko
Abstract
We investigate the MAX-$k$-CUT problem on hypergraphs by considering their representation as spin systems with Ising interactions. The corresponding cost Hamiltonian for MAX-$k$-CUT problem on hypergraphs is reduced to an Ising Hamiltonian with pairwise interactions. This reduction simplifies the solution of the MAX-$k$-CUT problem using quantum computing. As illustrative examples, a 3-uniform tight-star hypergraph and a sunflower hypergraph are considered. The corresponding Hamiltonians are constructed, and quantum protocols for the MAX-$k$-CUT problems are presented. The MAX-3-CUT and MAX-4-CUT instances are investigated for these hypergraphs by varying the number of Quantum Approximate Optimization Algorithm (QAOA) layers from (p=2) to (p=15) with quantum computing on IBM's Qiskit AerSimulator.
AI Summary
The paper studies QAOA formulations of MAX-$k$-CUT on hypergraphs using pairwise Ising interactions. Each hyperedge is replaced by a weighted clique, and contributions from overlapping hyperedges are combined. The resulting objective maximizes the weighted number of separated vertex pairs within hyperedges, favoring balanced splits of individual hyperedges rather than simply counting nonmonochromatic hyperedges. For a hyperedge of size $n$ split into groups of sizes $n_1,n_2$, the Ising energy is $\omega_e[\binom{n}{2}-2n_1n_2]$, minimized by an equal or near-equal split. For $k$ groups, the construction uses one-hot encoding with $k|V|$ qubits, an initial product of $W_k$ states, and a parity-partitioned ring $XY$ mixer that preserves feasibility. After combining repeated pairs, the interaction graph has at most $\binom{|V|}{2}$ distinct vertex pairs. Numerical tests use Qiskit AerSimulator, COBYLA with at most 2,000 iterations, and 10,000 shots, on a five-vertex 3-uniform tight star and a six-vertex sunflower, with $k=3,4$ and depths $p=2,5,10,15$. Reported approximation ratios are $0.73$–$0.82$ and $0.88$–$0.94$ for the tight star at $k=3,4$, respectively; sunflower ratios are $0.67$–$0.86$ and $0.75$. Some runs have an optimal assignment as the most frequent measurement outcome, although their expected cut values remain suboptimal. The paper identifies trapping in local minima as a limitation: increasing depth does not consistently improve performance. Evidence consists of these small simulator examples rather than hardware experiments or general approximation guarantees.
Central claim may not hold: The proposed pairwise Hamiltonian optimizes separated vertex pairs within hyperedges, which can select a suboptimal solution for standard hypergraph MAX-k-CUT, where each nonmonochromatic hyperedge contributes its weight once. The reported approximation ratios apply to the clique-expanded pair-counting objective and are not established as approximation ratios for standard hypergraph MAX-k-CUT.
Written by gpt-6.1-sol from the paper's full text. Automated: it can be wrong.