explicit_construction

Prove existence statements with concrete witnesses in Lean 4.

1|Updated Mar 14, 2026
One-click install
npx skills add https://github.com/bneb/perqed --skill explicit-construction
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: explicit_construction
Source: https://github.com/bneb/perqed/tree/main/.agents/skills/explicit_construction
Command: npx skills add https://github.com/bneb/perqed --skill explicit-construction

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Explicit construction provides concrete witnesses for existential statements, enabling direct verification rather than relying on non-constructive arguments.

Core Features & Use Cases

  • Witness-based proofs: supply a specific object and a proof that it satisfies the property.
  • Lean 4 integration: uses Lean 4 tactics like exact, refine, and decide to discharge goals.
  • Apply to Ramsey-type problems and bijections: embed witnesses into Lean terms for formal verification.

Quick Start

Provide a concrete witness and verify its property inside a Lean 4 proof.

Frequently Asked Questions about explicit_construction

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I prove an existence statement in Lean 4 using a concrete witness?

To prove an existence statement in Lean 4, provide a specific witness object and use tactics like exact or refine to verify that the object satisfies the required property. This direct construction avoids non-constructive arguments.

What is constructive proof in Lean 4 and when do I need an explicit witness?

Constructive proof in Lean 4 requires presenting a concrete object alongside a proof of its property. You need an explicit witness when formalizing existence statements for tasks like Ramsey-type proofs or bijection constructions.

How do I use the refine and exact tactics to construct proofs in Lean 4?

Use the refine tactic to structure a proof goal around a concrete witness, then apply exact to discharge remaining goals by providing the specific proof term that verifies the witness satisfies the property.

Can I use constructive mathematics to verify Ramsey-type proofs in Lean 4?

Yes, you can verify Ramsey-type proofs in Lean 4 by embedding concrete witnesses into Lean terms. This approach satisfies formal verification requirements by constructively proving the existence of the required structures.

Does the decide tactic work for constructive existence proofs in Lean 4?

The decide tactic works alongside exact and refine to discharge goals in constructive existence proofs. It evaluates concrete witnesses to verify their properties, satisfying Lean 4 proof script requirements for formal verification tasks.