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:

1. •Physical Intermediary - An object that enables physical connection (adapters, couplers, buffers)
2. •Process Intermediary - An agent or service that facilitates interaction (brokers, translators, routers)
3. •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:

1. •Direct Challenge: New user lacks knowledge to configure 30+ settings correctly
2. •Intermediary Requirements: Guide user through decisions without overwhelming them
3. •Intermediary Design: Step-by-step onboarding wizard with contextual help
4. •Interface Optimization:
   • •Start screen with single "Get Started" button
   • •Completion screen with "Launch Application" transition
5. •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)