Optimality of Greedy for Single-Pass Semi-Streaming Matching
Can any single-pass semi-streaming algorithm beat the naive greedy $1/2$-approximation for maximum matching? No. No single-pass semi-streaming algorithm, deterministic or randomized, achieves a better-than-half approximation, so greedy is optimal. The same construction settles the optimal competitive ratio of online matching with preemption at $1/2$.
Exact FrontierDelta
Scope and record
Occurred: Jul 20, 2026
Delta type: SOURCE CLAIM
Assumptions: VibeMathed verification: unreviewed. Publication: preprint. AI contribution: ai-co-developed. Imported under CC BY 4.0.
Canonical aliases: Optimality of Greedy for Single-Pass Semi-Streaming Matching · Semi-streaming matching
Confidence: Not scored
Registry verification: unreviewed · preprint · resolved
Attribution
VibeMathed
registry · event recorded by
Claude Fable 5
model · ai model contributor · Anthropic / OpenAI / Google
GPT-5.6 Sol
model · ai model contributor · Anthropic / OpenAI / Google
Claude Opus 5
model · ai model contributor · Anthropic / OpenAI / Google
Sepehr Assadi
human · human collaborator
Max Jiang
human · human collaborator
Mars Xiang
human · human collaborator
Gemini
model · ai model contributor · Anthropic / OpenAI / Google
Lineage and corrections
This event attributed to Sepehr Assadi
This event attributed to Max Jiang
This event attributed to Mars Xiang
This event attributed to Claude Fable 5
This event attributed to Gemini
This event attributed to GPT-5.6 Sol
This event attributed to Claude Opus 5