Research Article
A Hybrid IP/GA Approach to the Parallel Production Lines Scheduling Problem
Table 1
The complexity research of various parallel machine problems in the 1970s.
| Literature | Year | Problem variants | Complexity |
| Karp [3] | 1972 | | NP-hard | Bruno et al. [4] | 1974 | | NP-hard |
Lenstra [5] | 1977 | | NP-hard | Garey and Johnson [6] | 1978 | | NP-complete | Horowitz and Sahni [29] | 1976 | | |
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