Hierarchical Summarization

Hierarchical summarization mirrors the structure of the document itself. Rather than treating all chunks equally, it compresses content level by level:

• Pages → section summaries
• Sections → chapter summaries
• Chapters → document summary

Each level is a compressed representation of the level below. This is how humans summarize books — reading chapters, forming mental summaries, then integrating.

Hierarchical summarization is the right choice for:

• Books: 200+ pages with clear chapter structure
• Research papers: abstract, introduction, methods, results, discussion
• Legal contracts: sections with defined headings (definitions, obligations, termination)
• Technical reports: executive summary → findings → appendices

It is overkill for short articles. It shines when the document has a natural tree structure.