lev-os TRIZ Intermediary (Principle #24)
Overview
Intermediary is one of Genrich Altshuller's 40 Inventive Principles from TRIZ (Theory of Inventive Problem Solving), derived from analysis of over 200,000 patents. The principle states: use an intermediary carrier article or intermediary process to enable, improve, or protect the interaction between two elements.
The core insight: when direct interaction is impossible, inefficient, or harmful, introduce a third element to mediate the relationship. The intermediary can transform, translate, buffer, or optimize the connection without requiring changes to the original elements.
Intermediary appears in three forms:
- Physical Intermediary - An object that enables physical connection (adapters, couplers, buffers)
- Process Intermediary - An agent or service that facilitates interaction (brokers, translators, routers)
- Temporal Intermediary - A mechanism that manages timing mismatches (queues, caches, schedulers)
When to Use
- Two elements cannot connect directly due to incompatibility
- Direct interaction would damage one or both elements
- The interaction needs translation, transformation, or buffering
- Modifying the original elements is impractical or expensive
- You need flexibility to change one element without affecting the other
- Distribution, aggregation, or routing is required
- Safety concerns prevent direct contact
The Process
Step 1: Identify the Direct Interaction Challenge
What prevents or degrades direct connection between the two elements?
Example: Vacuum cleaner motor generates high suction but cannot navigate tight spaces.
Step 2: Define Intermediary Requirements
What must the intermediary do to solve the interaction problem?
Requirements Categories:
- Physical Translation: Size, shape, material compatibility
- Property Transformation: Voltage conversion, speed reduction, pressure regulation
- Routing/Distribution: One-to-many, many-to-one, selective routing
- Protection: Shield from heat, chemicals, electrical discharge
- Temporal Buffering: Absorb timing mismatches, smooth bursts
Example: Intermediary must be flexible to navigate corners while maintaining suction.
Step 3: Design or Select the Intermediary
Choose the simplest intermediary that meets requirements.
Example: Flexible hose with internal ribbing for structural integrity.
Step 4: Optimize Interface Points
Ensure clean, efficient connection at both ends of the intermediary.
Example: Standardized coupling at motor end, swivel joint at attachment end.
Step 5: Test End-to-End Performance
Verify that the intermediary enables the desired interaction without introducing new problems.
Example: Measure suction loss through hose, test durability under repeated flexing.
Example Application
Situation (Software Onboarding Complexity): New users struggle with complex software setup, leading to high abandonment rates.
Application:
- Direct Challenge: New user lacks knowledge to configure 30+ settings correctly
- Intermediary Requirements: Guide user through decisions without overwhelming them
- Intermediary Design: Step-by-step onboarding wizard with contextual help
- Interface Optimization:
- Start screen with single "Get Started" button
- Completion screen with "Launch Application" transition
- Testing: A/B test shows wizard reduces abandonment from 40% to 12%
Outcome: 70% reduction in support tickets during first week, 28% increase in successful onboarding completions.
Anti-Patterns
- Adding intermediary when direct connection is actually possible
- Choosing an intermediary that is more complex than the problem
- Creating bottlenecks through slow or limited-capacity intermediaries
- Failing to maintain or upgrade the intermediary as needs evolve
- Over-relying on intermediaries instead of fixing underlying incompatibilities
- Introducing intermediaries that add latency or reduce quality unacceptably
- Not providing fallback when intermediary fails
Related
- adapter-pattern (software design pattern for interface compatibility)
- proxy-pattern (intermediary object controlling access to another)
- mediator-pattern (centralized coordination between multiple elements)
- translation-layer (transform data/protocols between systems)
- buffer-abstraction (temporal intermediary for rate mismatches)