flowchart LR
    A["Unstructured classification<br/>with overlap and omission<br/>degraded analytical reliability"] --"ME: no overlap<br/>CE: no omission"--> B["Complete and clear<br/>structural classification"] --"Logical persuasiveness<br/>and completeness"--> C["Analysis with no gaps<br/>persuading stakeholders"]

    style A fill:#FFEBEE,stroke:#D32F2F,color:#000
    style B fill:#E3F2FD,stroke:#1976D2,color:#000
    style C fill:#E8F5E9,stroke:#388E3C,color:#000
  

    flowchart TD
    subgraph R1["　"]
        direction LR
        ME["Mutually Exclusive<br/>(no overlap)<br/>Each item is independent;<br/>no single item belongs<br/>to two categories at once"]
        CE["Collectively Exhaustive<br/>(no omission)<br/>Includes every possibility;<br/>no item exists<br/>outside the classification"]
    end
    subgraph R2["　"]
        direction LR
        OK["MECE satisfied<br/>A complete classification<br/>with no overlap<br/>and no omission"]
        FAIL["MECE violation types<br/>overlap only,<br/>omission only,<br/>or both"]
    end

    style ME   fill:#E3F2FD,stroke:#1976D2,color:#000
    style CE   fill:#E8F5E9,stroke:#388E3C,color:#000
    style OK   fill:#1E3A5F,stroke:#1E3A5F,color:#fff
    style FAIL fill:#FFEBEE,stroke:#D32F2F,color:#000
    style R1 fill:none,stroke:none
    style R2 fill:none,stroke:none
  

    flowchart TD
    PROB["Problem Definition<br/>IT system performance degradation"]

    subgraph MECE_TREE["MECE Issue Tree"]
        direction LR
        L1A["Infrastructure causes<br/>server, network,<br/>storage issues"]
        L1B["Application causes<br/>code, query,<br/>memory leaks"]
        L1C["External causes<br/>traffic spikes,<br/>third-party APIs"]

        L2A1["CPU overload"]
        L2A2["Network bandwidth saturation"]
        L2B1["Slow queries"]
        L2B2["Inefficient algorithms"]
    end

    PROB --> L1A & L1B & L1C
    L1A --> L2A1 & L2A2
    L1B --> L2B1 & L2B2

    style PROB fill:#1E3A5F,stroke:#1E3A5F,color:#fff
    style L1A  fill:#E3F2FD,stroke:#1976D2,color:#000
    style L1B  fill:#F3E5F5,stroke:#7B1FA2,color:#000
    style L1C  fill:#FFF3E0,stroke:#F57C00,color:#000
  

    flowchart LR
    S1["1. Define the core question<br/>Clearly express<br/>the problem to solve<br/>as a single question"]
    S2["2. First-level classification (ME)<br/>First decomposition<br/>into non-overlapping categories<br/>3-5 categories recommended"]
    S3["3. Verify completeness (CE)<br/>Check that every<br/>possibility is included;<br/>add any missing items"]
    S4["4. Further decomposition<br/>Recursively decompose<br/>each category using MECE<br/>to the needed level"]
    S5["5. Data and evidence<br/>Validate the hypothesis<br/>at each leaf node<br/>with facts and data"]

    S1 --> S2 --> S3 --> S4 --> S5

    style S1 fill:#E3F2FD,stroke:#1976D2,color:#000
    style S2 fill:#F3E5F5,stroke:#7B1FA2,color:#000
    style S3 fill:#FFEBEE,stroke:#D32F2F,color:#000
    style S4 fill:#FFF3E0,stroke:#F57C00,color:#000
    style S5 fill:#E8F5E9,stroke:#388E3C,color:#000