Duration: 20 minutes
For: Developers new to LLMs, verification, or trust-critical AI systems
Goal: Build the right mental model before touching any QWED API
- Proof vs. confidence
- What an LLM actually does
- Why hallucinations are inevitable
- Probabilistic vs. deterministic systems
- Why fail-closed verification matters
Before anything else, read:
These two lessons establish the distinction that drives the entire QWED ecosystem:
- parsing is not proof
- simplification is not verification
- confidence is not evidence
- unsupported is not approved
An LLM is a text prediction system trained on massive corpora.
It does not "know" facts the way a deterministic engine proves facts. It predicts likely continuations.
Prompt: "2 + 2 ="
LLM predicts: "4"
Prompt: "2843 + 7291 ="
LLM predicts a likely continuation, which may still be wrong- drafting language
- summarization
- translation
- extracting structured information
- conversational interaction
- exact arithmetic
- formal logic
- safety-critical execution decisions
- distinguishing a plausible answer from a proved answer
A hallucination is a plausible-sounding output that is still wrong.
This happens because LLMs optimize for pattern completion, not truth.
- wrong calculations
- fake legal citations
- invalid medical dosages
- invented policies, studies, or references
LLMs are probabilistic:
- they generate likely outputs
- they may vary across runs
- they can be helpful without being provable
Deterministic engines:
- follow exact rules
- produce the same result for the same input
- can prove or reject claims within supported domains
QWED uses the LLM as an untrusted translator and the deterministic engine as the trust decision layer.
User query -> LLM translation -> deterministic verification -> verified / invalid / unverifiable
Without verification:
- bugs ship to production
- users inherit silent trust failures
- "helpful" outputs can cause financial, legal, or safety harm
With verification:
- supported claims can be checked deterministically
- invalid claims can be blocked
- unsupported claims can be surfaced honestly as
UNVERIFIABLE
When QWED cannot establish proof, the answer should not silently degrade into:
- a fallback guess
- a lower confidence answer
- a default value that looks safe
The right outcomes are:
BLOCKEDUNVERIFIABLEQUARANTINEDHUMAN_REVIEW_REQUIRED
This is what makes QWED a trust-boundary system rather than just another AI helper.
- What is the difference between a useful answer and a verified answer?
- Why is confidence not the same thing as proof?
- What should happen when a claim is unsupported?
- Why is "safe default" often the wrong pattern for trust-critical AI?
If you can answer those clearly, you are ready for the rest of the course.