Cooperation Demo: tit4Taxi

The tit4Taxi project is a runnable proof of concept demonstrating how adjacent taxi cooperatives operating in exclusive, adjacent territories can cooperate to reduce empty return trips and fuel waste.

GitHub Repository: tonyx/tit4Taxi
Theoretical Explanation (YouTube): How Taxi Cooperatives Can Cooperate
Research Paper (Zenodo): Beyond the Tragedy of the Alleged Monopoly: A Commons-Based Cooperation Model with Weighted Reciprocity in the Taxi Sector

The Problem: Territorial Inefficiencies

When two taxi cooperatives (Coop A and Coop B) own exclusive transport rights in adjacent regions:

A taxi from Coop A drops a passenger off in Coop B’s territory.
Under strict local regulations, the Coop A driver cannot pick up a passenger in Coop B’s region, even if passengers are waiting to travel back to Coop A’s region.
The Coop A driver must return empty, resulting in wasted fuel, emissions, and time.

The Solution: Weighted Reciprocity Tokens

By framing the exclusive territory rights as a commons governance problem, tit4Taxi introduces a system of Weighted Reciprocity Tokens (a technical implementation of a Tit-for-Tat game theory strategy):

Token Economy: Cooperatives grant each other “transportation rights tokens” to allow picking up passengers in their exclusive territories.
Transaction Log: Every cross-territory pickup is recorded on the event store.
Balance Ledger: A shared ledger tracks token balances. A cooperative must maintain a healthy token balance to continue using the other cooperative’s roads, ensuring mutual cooperation and preventing free-riding.

graph TD
    subgraph Coop_A_Territory
        PA[Passenger wants to go to B]
        TA[Taxi from Coop A]
    end

    subgraph Coop_B_Territory
        PB[Passenger wants to go to A]
        TB[Taxi from Coop B]
    end

    TA -- "1. Drops passenger in B" --> Coop_B_Territory
    TA -- "2. Claims returning passenger PB" --> PB
    PB -- "3. Pays Coop B Reciprocity Token" --> TA
    TA -- "4. Returns with passenger to A" --> Coop_A_Territory

Architecture & Event Sourcing

Using Sharpino, the reciprocity token ledger is modeled as a consistent event-sourced domain:

Ledger Aggregate: Tracks token transactions, pending requests, and balances between cooperatives.