The Barbara Liskov
Framework
Abstraction & Behavioural Subtyping
Barbara Liskov represents one of the most distinctive thinking patterns in their field. Barbara Liskov's approach, captured in this framework as mental models, decision heuristics, and the signature questions they would ask.
The abstraction & behavioural subtyping framework distils Barbara Liskov's documented approach into a .md skill file you can load into Claude, ChatGPT, or any LLM in seconds.
Where most AI personas generate generic output, this framework is grounded in real documented work: interviews, writing, published frameworks, and the specific decisions Barbara Liskov made when it mattered. Use it for decision-making, writing, strategy, or any situation where you want your AI to think with Barbara Liskov's distinctive patterns rather than a default model voice.
A glimpse of Barbara Liskov's thinking.
Abstraction should hide implementation details while preserving behavioral contracts. Subtyping must maintain the semantic meaning of operations—clients should never need to know which specific subtype they're working with. The power of object-oriented design lies not in clever inheritance tricks, but in creating predictable, substitutable abstractions.
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Five specific models, each named and explained with concrete examples, unlocked with purchase.
"What behavioral promises does this parent class make that every subclass must honor?"
4 more questions in Barbara Liskov's voice are unlocked with purchase.
Full list of anti-patterns unlocked with purchase.
The full framework adds: detailed explanations of all five mental models with real-world examples, the decision heuristics Barbara Liskov actually used, remaining signature questions, the complete list of anti-patterns, a copy-paste activation prompt, and a worked example.
Unlocked the moment you purchase. ~2,000 words total. Delivered as a Claude Skill and plain .md within 60 seconds of checkout.
- ✦Core philosophy: 2–3 sentences grounded in Barbara Liskov's documented worldview
- ✦Five signature mental models: each named, with concrete examples from their work
- ✦Decision heuristics: the concrete rules they actually used
- ✦Signature questions: five questions that sound like Barbara Liskov, not a generic MBA
- ✦What they would NOT do: the anti-patterns this framework rejects
- ✦Copy-paste activation prompt: drop straight into Claude or ChatGPT
- ✦Worked example: the framework applied to a realistic scenario
- →barbara-liskov.zip: a native Claude Skill. Upload to Settings → Skills in Claude, or unzip to
~/.claude/skills/ - →barbara-liskov-framework.md: plain markdown. Works in ChatGPT Custom GPTs, Gemini, Claude Projects, agent system prompts, anywhere
What it does with a real question.
A founder is deciding whether to take a large but difficult client.
My judgment: take the client only if you can state, in writing, what your company promises to do for them, and that promise is one you would also make to your smallest customer.
The danger with a large, difficult client is that they will pull your company toward custom behavior. Every special request, an exception here, a bespoke report there, quietly rewrites what your product or service is. Soon you have one offering that behaves differently depending on who is using it, and your other clients and your own team can no longer predict what you will do. That is a substitution failure at company scale: the new client cannot be swapped in for the existing ones without breaking something.
So test it. Take their five hardest likely demands and ask whether you could grant each one without weakening anything you already guarantee to current customers. A demand that adds to what you deliver, such as faster response or a stricter report, is usually safe. A demand that relaxes your terms or requires your team to know "this account is special" is a sign you would be building a hidden branch in your business.
Large size makes this worse, because their revenue gives them leverage to keep asking.
Your next move: before the next call, draft a one-page statement of exactly what you will and will not do for them, and see whether they will sign it. If they refuse the boundaries, you have your answer.
The full framework carries five models, decision heuristics, signature questions and a worked example.
Written by claude-sonnet-5-5 with this framework loaded, 2026-10-11. Checked automatically for length and for copied framework text.
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Ten minds that shaped how software is actually built
Get Barbara Liskov plus nine more for $29.99 →Inspired by the documented thinking of Barbara Liskov. A mental-model toolkit, not a literal representation. Delivered as a .md file compatible with Claude, ChatGPT, Gemini, and any LLM.