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arXiv:2603.04977 ★ 75 Mar 5, 2026

VideoHV-Agent: a four-agent “hypothesis first, search second” framework

Key result

An LLM doesn't hallucinate when it weighs competing theories. It does something worse — it looks for confirmation of whichever theory showed up first and ignores the facts that point the other way. The Hypothesis-Verification method lets you find the real cause among several theories — through explicit, testable hypotheses instead of gut feeling. The trick: don't ask 'what is true here?' — ask 'what must be true if option A is right? if B is right?' Thinker writes the conditions for each option, Judge finds one discriminating clue — the minimal piece of evidence that separates the hypotheses rather than confirming one of them. Then Verifier checks the clue against the data. The search isn't broad — it's surgical.

01

TL;DR

Hypothesis-Verification is a technique that rewires how analysis works: instead of “go dig up something on the topic,” you first spell out what exactly has to be true for each answer option to be correct. Only then do you go hunting for evidence.

The standard “wander through the topic and collect whatever you find” approach falls apart on hard problems: the first facts you stumble on send the reasoning down the wrong path, and every next step doubles down on the initial mistake. Worse, the model looks for what resembles an answer rather than what actually separates the right option from the wrong ones.

The method fixes this with four roles inside one task: Thinker rewrites each answer option as a testable hypothesis, Judge finds the minimal clue — the one piece of evidence that splits the hypotheses, Verifier checks that clue against the actual data, and Answer pulls it all together into a final conclusion with an explicit chain of reasoning.

Want this for your own case? Apply this study to your task: AI adapts its method to what you are working on and writes the prompt.

02

Method Blueprint

(All four steps can run in a single prompt)

STEP 1 — Thinker: for each answer option, formulates a hypothesis
         "What has to be true for answer X to be correct?"
         → list of hypotheses H1, H2, H3...

STEP 2 — Judge: from the set of hypotheses, derives one discriminating clue
         "What do we need to check to tell the hypotheses apart?"
         → one specific clue κ

STEP 3 — Verifier: checks the clue against the available data
         → status CONFIRMED / PARTIAL / NOT CONFIRMED + justification

STEP 4 — Answer: integrates the evidence and states the final answer
         → conclusion with an explicit chain of logic

If status is NOT CONFIRMED → refinement loop: hypotheses get sharpened
and the check repeats (usually 1-2 times)
03

Example in Action

Task: Paul opened a dumpling shop on Uber Eats four months ago. His average rating is 3.8 — not good. There are three theories: (A) bad food, (B) slow delivery, (C) a weak listing page. He needs to find the real cause without guessing.

Prompt:

Act as an analyst using the four-agent Hypothesis-Verification scheme.

Context: 3.8 rating on Uber Eats, 40 reviews over 4 months.
Reviews: [paste 10-15 reviews]
Possible causes: A) the food tastes bad, B) slow delivery, C) weak
listing/photos

THINKER — formulate a hypothesis for each option:
What specifically must be true in the reviews if the cause is A?
What must be true if the cause is B?
What must be true if the cause is C?
(key entities, actions, time patterns)

JUDGE — from the three hypotheses, derive one discriminating clue:
What minimal observation in the reviews would separate these three hypotheses?
What do we need to find to rule out two of the three?

VERIFIER — check the clue against the reviews:
Find direct evidence. Output a status:
CONFIRMED / PARTIAL / NOT CONFIRMED + timestamps / quotes

ANSWER — integrate the evidence:
Which theory got confirmed?
What is ruled out and why? Recommendation in one action.

Result: The model will first lay out three explicit hypotheses — not “bad delivery,” but “reviews mention a specific wait time over X minutes and tie it to the low score.” Then it derives a discriminating clue — one phrase or pattern that shows up only if one of the theories is true. Next it searches the reviews for that clue and reports what it found. The final answer points explicitly to the evidence — logic, not gut feeling.

04

Why It Works

A plain question like “why is my rating low?” triggers a search for things that look similar — and the model grabs the first confirming facts while ignoring the ones that point the other way. This is called confirmation bias: an LLM generates text by following the most likely pattern, and early reasoning drags everything after it along.

LLMs have another strength, though: they handle explicitly assigned roles and structured conditions really well. Ask not “what is true?” but “what would have to be true?” and the model switches from hunting for confirmation to writing out testable conditions.

The method exploits exactly that: Thinker forces the model to explicitly unpack the logic of each theory, and Judge finds the separating clue — what distinguishes the theories, not what they share. From there the search goes narrow instead of wide: not “collect everything about delivery,” but “find exactly this.”

Control knobs: - Number of hypotheses → more answer options = more hypotheses; you can cap it at the 2-3 most likely - Clue format → ask Judge to list the specific marker words to look for in the text - Verifier status → add a threshold: “count as CONFIRMED only if the clue appears in 3+ reviews” - Refinement loop → drop it for simple tasks to save time and tokens

05

Prompt Template

Work using the Hypothesis-Verification scheme. Task: {task description}.
Answer options: {A: ..., B: ..., C: ...}
Data to analyze: {text / reviews / facts}

THINKER:
For each option — what must be true in the data
if that option is the correct one? Name key entities, actions,
patterns. Drop clearly implausible options right away.

JUDGE:
From the set of hypotheses, derive one discriminating clue κ.
This is the minimal observation that separates the correct hypothesis
from the rest. What do we need to find — and what does it look like concretely?

VERIFIER:
Check clue κ against the data. Output a status:
CONFIRMED / PARTIAL / NOT CONFIRMED
+ concrete evidence (quotes, facts, timestamps)

If PARTIAL — specify what exactly is confirmed
and what still needs checking.

ANSWER:
Integrate the evidence. Which option is correct and why?
What is ruled out? Final conclusion: {output format}.

Placeholders: - {task description} — what you are analyzing and why - {A, B, C} — competing theories / options / hypotheses - {text / reviews / facts} — the data you check against - {output format} — e.g. “one action,” “ranking of options,” “yes/no with justification”


🚀 Quick start — paste into the chat:

Here is a Hypothesis-Verification template. Adapt it to my task: {your task}.
Ask me questions to fill in the fields.

[paste the template above]

The LLM will ask which competing theories you are weighing and what data you have — because without that, Thinker can't write hypotheses that actually differ. It will take the four-agent structure and tailor the roles to your task.

06

Limitations

⚠️ Open-ended questions: The method is built for choosing between competing options. For an open question with no answer options it is less effective: Judge can't come up with a discriminating clue when there is nothing to tell apart.

⚠️ Data quality: If the source data is thin or uniform, Verifier won't find the clue — the status will loop on PARTIAL. You need enough facts to compare.

⚠️ Task complexity: For simple questions with an obvious answer it's overkill. The structure pays off on genuinely competing hypotheses where gut instinct can be wrong.

⚠️ Refinement loop: If the task is poorly structured, the self-refinement loop can spin forever — the model keeps rephrasing hypotheses without real progress. Cap it at 2 iterations.

07

Resources

Title: Think, Then Verify: A Hypothesis-Verification Multi-Agent Framework for Long Video Understanding

Datasets and benchmarks: EgoSchema, NextQA, IntentQA, VideoMME-L

Authors: Zheng Wang, Haoran Chen, Haoxuan Qin, Zhipeng Wei, Tianwen Qian, Cong Bai

Institutions: Zhejiang University of Technology (China), UC Berkeley (USA), East China Normal University (China)

Code: https://github.com/Haorane/VideoHV-Agent

Research digest

Key result

An LLM doesn't hallucinate when it weighs competing theories. It does something worse — it looks for confirmation of whichever theory showed up first and ignores the facts that point the other way. The Hypothesis-Verification method lets you find the real cause among several theories — through explicit, testable hypotheses instead of gut feeling. The trick: don't ask 'what is true here?' — ask 'what must be true if option A is right? if B is right?' Thinker writes the conditions for each option, Judge finds one discriminating clue — the minimal piece of evidence that separates the hypotheses rather than confirming one of them. Then Verifier checks the clue against the data. The search isn't broad — it's surgical.

Principle

The question 'what is true here?' is a trap. The model looks for similar things and finds the first facts that fit. Early reasoning pulls the rest in the same direction. Found complaints about taste — goes looking for more complaints about taste. Four roles in one prompt: Thinker — writes hypotheses: 'If the cause is slow delivery, the reviews should contain...' Judge — finds one discriminating clue: not 'everything about delivery,' but 'a specific pattern that only one of the theories has' Verifier — checks the clue against the data, outputs a status: confirmed / partial / no + quotes Answer — final conclusion with an explicit chain of logic, not intuition Judge is the most important link. It doesn't look for evidence for one theory — it looks for what tells the theories apart. If no clue turns up, that's information too: the hypotheses get sharpened and the loop repeats (no more than twice).

Why it works

A regular prompt like 'why is the rating low?' kicks off a confirmation search. The model generates the next token along the most likely pattern — and early reasoning drags everything else the same way. That's not a bug, it's the nature of a language model. The question 'what must be true?' flips the mode: the model stops hunting for confirmation and starts writing testable conditions. It's the difference between 'find evidence against the suspect' and 'tell me what would prove each of the three right.' Judge adds a second shift. Instead of broad collection — a pinpoint check of one distinguishing fact. The minimal evidence that one theory predicts and the other two don't. That's what exposes the right answer quickly and without extra noise.

When to apply

Diagnosing business problems — when you have 2-4 competing theories about the cause and data to check them against: reviews, metrics, facts, documents. Reviewing strategic decisions — when you're choosing between approaches and need logic, not intuition. Analyzing drop-offs — why people didn't buy, didn't show up, didn't stay. NOT a fit for open questions with no answer options — Judge can't find a discriminating clue when there's nothing to tell apart. If the data is scarce or uniform, Verifier will get stuck looping on 'partial.'

Mini recipe

1. State the task and the options: what you're analyzing + 2-4 competing theories. Without options the method doesn't work — if you don't have any, ask the model to generate the most likely ones first. 2. Thinker: for each option — what must be true in the data if that one is correct? Concrete words, patterns, timestamps — not abstractions. 3. Judge: from the set of hypotheses — one discriminating clue. What do we need to find to rule out two of the three theories? What does it look like concretely? 4. Verifier: check the clue against the data with an explicit status (confirmed / partial / no) plus quotes or facts. If partial — what else needs checking? 5. Answer: integrate the evidence and produce the final answer with a chain of logic and a one-action recommendation.

Examples

[BAD]: `Why does my dumpling shop have a 3.8 rating? Here are the reviews: [list]. What's wrong?` [GOOD]: `Work using the Hypothesis-Verification scheme. Context: food delivery, 3.8 rating, 40 reviews over 4 months. Options: A) bad food, B) slow delivery, C) weak listing. Data: [paste reviews] THINKER: for each option — what must be true in the reviews if that one is correct? Keywords, patterns, specific timestamps. JUDGE: from the three hypotheses — one discriminating clue. What separates one theory from the other two? What does it look like concretely in the review text? VERIFIER: find the clue in the reviews. Status: confirmed / partial / no + direct quotes. ANSWER: which option is correct and why? What is ruled out? Recommendation in one action.`

In plain words

The gist: modern AI models freeze up when you feed them long videos or huge piles of data. They suffer from confirmation bias: ask “why does the food taste bad?” and the model will helpfully dig up a couple of angry reviews and ignore a hundred complaints about cold delivery. It latches onto the first fact it sees and builds a theory around it, even if the theory is total nonsense. The Hypothesis-Verification method breaks that script by making the AI work not like a lazy viewer but like a meticulous detective who first builds theories and then tries to tear them apart.

It's like losing your keys: instead of running around the apartment at random, you sit down and make a list: “If they're in my jacket, I hung it in the closet” or “If they're in the door, I never took them out.” You're not looking for “keys in general,” you're testing a specific hypothesis. Without this method the model acts like someone who walks into a room, sees an apple on the table and decides it's a kitchen, when they're actually in a biology classroom. Technically there's a clue, but the context is completely blown.

Instead of a lazy “what's going on here?”, the system runs a four-step loop. First it generates candidate answers, then for each answer it writes verification hypotheses — what exactly must appear in the video for that answer to be true. Next comes evidence gathering at specific timestamps and, finally, the final verdict. If we're checking why a dumpling shop has a low rating, the model doesn't just skim the reviews — it hunts for specific clues: “are there complaints about raw dough?” or “do people mention the driver showing up late?” That turns reading tea leaves into a structured audit.

Although the method was tested on long videos, where you have to keep tons of details in memory, the principle is universal. It's a perfect fit for any analysis where there's too much data and mistakes are expensive: from digging through server logs to reviewing quarterly reports. When you make the model think “what if?” first and look for proof second, you switch off its “hallucinating storyteller” mode. Logic beats patterns, and it's the only way to get an LLM to produce results you can trust.

Bottom line: stop asking the model to “analyze the text” — make it test hypotheses. The Hypothesis-Verification method turns the model from a skim-reader into a ruthless fact-checker. If you don't build this into your prompts, you'll keep getting answers that look logical but have nothing to do with reality. Either you control the search logic, or the model feeds you hallucinations.

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Based on VideoHV-Agent: a four-agent “hypothesis first, search second” framework arXiv:2603.04977

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