The enumeration problem for connective graphs with one nontrivial block was discussed by the theory of combinatorics, and the new conclusion is also given.
利用组合理论和图的计数理论，讨论了只含有一个非平凡块的连通图的计数问题，给出了新的结论。
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The essay has a study on enumeration question labeled oriented connected graphs with only one cut vertices and labeled oriented connected graphs that all of cut vertices are in same block.
Low Density parity check (LDPC) codes are a kind of linear block codes approaching Shannon limit. They can be constructed either with spare parity-check matrix or with factor graphs.