Multi-agent systems and smart contracts

smart contract

Smart contracts are programmes that run on the blockchain and can refer to contracts that are automatically executed when certain conditions are met.

Specifically, a smart contract is a contract written in code, which can control transactions and change their state, is capable of automatic execution, is a framework that does not require an intermediary, and when certain conditions are met, a process determined based on the code is executed and the post-execution The results are recorded in the blockchain and are difficult to tamper with.

Features of smart contracts include

• Transparency: the code is public and can be audited by anyone.
• Automation: execution is instantaneous when conditions are met.
• Reliability: runs on a distributed network, resulting in almost zero downtime.
• Irreversibility: once deployed, it is difficult to change.

Applications of smart contracts include.
1. financial:
– Decentralised finance (DeFi): e.g.) lending, borrowing and staking.
– Token issuance: token creation based on ERC-20 (Ethereum standard).

2. supply chain:
– Logistics and product tracking.
– Condition-based payment processing (e.g. automatic payment on arrival of goods).

3. non-fiat tokens (NFTs):
– Buying and selling digital art and in-game assets.

4. digital identity:
– Management and authentication of personal data.

5. governance:
– DAOs (Decentralised Autonomous Organisations): automation of voting and decision-making.

Advantages and disadvantages of smart contracts include the following

Advantages:
– Efficient: reduced manual contracting processes.
– Reliable: provides trust without a central authority.
– Low cost: reduced intermediary fees.

Disadvantages:
– Security risks: code vulnerabilities can be exploited.
– Unchangeable: difficult to fix bugs.
– Cost: transaction fees (gas prices) for blockchains can rise.

Smart contract language

Some of the main smart contract languages are described below.

• Solidity: Solidity is a general language for writing smart contracts for the Ethereum blockchain and is the official and widely used smart contract language of Ethereum.Solidity is a statically typed language, which means that special structures such as events, modifiers It will also be one that supports special structures such as.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract SimpleStorage {
    uint256 public storedData;

    // Functions for setting data
    function set(uint256 _data) public {
        storedData = _data;
    }

    // Functions to retrieve data
    function get() public view returns (uint256) {
        return storedData;
    }
}

DESCRIPTION: This smart contract has simple storage capabilities and can store and retrieve data.

• Vyper: Vyper is a smart contract language for Ethereum that is considered more secure and safe than Solidity; Vyper has a simple syntax similar to Python, with an emphasis on readability and security.

# @version ^0.3.0

storedData: public(uint256)

@external
def set(_data: uint256):
    self.storedData = _data

@view
@external
def get() -> uint256:
    return self.storedData

DESCRIPTION: A storage contract written in Vyper, which achieves much the same functionality as the Solidity example. The code is concise and can be designed to be gas-efficient.

• Chaincode: Chaincode is the smart contract language used in the Hyperledger Fabric blockchain framework.Chaincode is mainly written in the Go language, but recently other programming languages (Java, JavaScript, TypeScript, etc.) are also supported.

package main

import (
	"encoding/json"
	"fmt"

	"github.com/hyperledger/fabric-contract-api-go/contractapi"
)

type SmartContract struct {
	contractapi.Contract
}

type Data struct {
	ID   string `json:"id"`
	Data string `json:"data"`
}

// Save data.
func (s *SmartContract) Set(ctx contractapi.TransactionContextInterface, id string, data string) error {
	dataEntry := Data{
		ID:   id,
		Data: data,
	}
	dataAsBytes, _ := json.Marshal(dataEntry)
	return ctx.GetStub().PutState(id, dataAsBytes)
}

// Get data.
func (s *SmartContract) Get(ctx contractapi.TransactionContextInterface, id string) (*Data, error) {
	dataAsBytes, err := ctx.GetStub().GetState(id)
	if err != nil {
		return nil, fmt.Errorf("failed to read from world state: %v", err)
	}
	if dataAsBytes == nil {
		return nil, fmt.Errorf("the id %s does not exist", id)
	}
	data := new(Data)
	_ = json.Unmarshal(dataAsBytes, data)
	return data, nil
}

func main() {
	chaincode := new(SmartContract)
	contractapi.NewChaincode(chaincode).Start()
}

DESCRIPTION: It is a simple smart contract that stores and retrieves data in the world state (world state) of Hyperledger Fabric.

• Michelson: Michelson is the smart contract language of the Tezos blockchain; Michelson is based on a functional programming style and is suitable for formal verification and formal inspection.

parameter string;
storage string;
code {
  CAR;      # Get input values.
  SWAP;     # ストレージと交換
  NIL operation;
  PAIR;
}

DESCRIPTION: This Michelson contract would simply be a smart contract that updates the storage; it receives input data in the parameter and updates the storage.

These languages are summarised below.

These are some representative smart contract languages, but some blockchain platforms may use their own languages. In addition, many platforms nowadays support integration with different programming languages, allowing a wider developer base to create smart contracts.

Combining multi-agent technology and smart contracts

The combination of multi-agent technology and smart contracts enables the creation of autonomous systems in distributed environments. This will enable increased reliability, efficiency and automation between agents. Specific examples and feasible application areas are described below.

1. basic concepts of multi-agent and smart contract cooperation

Role of smart contracts:

• Act as a trusted intermediary and guarantee transactions and agreements between agents.
• Automates fraud prevention and conditional transactions.

Role of multi-agents:

• Each agent acts autonomously and makes decisions according to the situation.
• Agents are responsible for data collection, negotiation, planning and execution.

2. basic structure of the implementation

Relationship between agents and smart contracts:

1. Agents:
   • It is an independent programme and carries out tasks.
   • Communicates with the smart contract and requests the necessary data and transactions.
2. Smart contracts:
   • Holds rules and terms of agreement shared between agents.
   • Processes and records requests from agents.

Example implementations:

Smart contracts (Solidity): The following is an example of a smart contract that manages resource transactions between agents.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract ResourceExchange {
    struct Resource {
        string name;
        uint256 quantity;
        address owner;
    }

    mapping(uint256 => Resource) public resources;
    uint256 public resourceCount;

    event ResourceAdded(uint256 id, string name, uint256 quantity, address owner);
    event ResourceTransferred(uint256 id, address from, address to);

    function addResource(string memory _name, uint256 _quantity) public {
        resources[resourceCount] = Resource(_name, _quantity, msg.sender);
        emit ResourceAdded(resourceCount, _name, _quantity, msg.sender);
        resourceCount++;
    }

    function transferResource(uint256 _id, address _to) public {
        require(resources[_id].owner == msg.sender, "Not the owner");
        resources[_id].owner = _to;
        emit ResourceTransferred(_id, msg.sender, _to);
    }
}

Agent (Python + Web3.py): This is an example of an agent interacting with a smart contract.

from web3 import Web3

# Connection to Ethereum nodes
w3 = Web3(Web3.HTTPProvider('http://127.0.0.1:8545'))

# Smart contract addresses and ABIs
contract_address = "0xYourContractAddress"
abi = [
    # Insert ABI definition here.
]

contract = w3.eth.contract(address=contract_address, abi=abi)

# Agents add resources.
def add_resource(name, quantity, private_key):
    account = w3.eth.account.from_key(private_key)
    tx = contract.functions.addResource(name, quantity).buildTransaction({
        'from': account.address,
        'nonce': w3.eth.getTransactionCount(account.address),
        'gas': 2000000,
        'gasPrice': w3.toWei('50', 'gwei'),
    })
    signed_tx = w3.eth.account.signTransaction(tx, private_key)
    w3.eth.sendRawTransaction(signed_tx.rawTransaction)

# Transfer resources.
def transfer_resource(resource_id, to_address, private_key):
    account = w3.eth.account.from_key(private_key)
    tx = contract.functions.transferResource(resource_id, to_address).buildTransaction({
        'from': account.address,
        'nonce': w3.eth.getTransactionCount(account.address),
        'gas': 2000000,
        'gasPrice': w3.toWei('50', 'gwei'),
    })
    signed_tx = w3.eth.account.signTransaction(tx, private_key)
    w3.eth.sendRawTransaction(signed_tx.rawTransaction)

3. applications

1. supply chain management

• Multiple agents (factories, warehouses, distributors) manage resources (parts and products).
• Smart contracts automate inventory management and contractual terms (e.g. payment on arrival of products).

2. energy trading

• Agents manage demand and supply of renewable energy.
• Smart contracts trade energy credits.

3. automated vehicle communication

• Exchange data between vehicles (e.g. traffic conditions, toll settlements).
• Smart contracts record the terms of toll payment and data sharing.

4. decentralised autonomous organisations (DAOs)

• Multiple agents participate in governance.
• Voting and decision-making is carried out via smart contracts.

4. implementation challenges

Challenges:

1. Transaction costs: High gas costs for smart contract execution limit agent activity.
2. Scalability: Potential processing delays if a large number of agents access smart contracts at the same time.
3. Security: Security of smart contracts needs to be strengthened to take into account the possibility of agents taking malicious action.

reference book

This section discusses reference books on smart contracts and multi-agent systems.

Smart contracts
1. ‘Mastering Ethereum’.
Authors: Andreas M. Antonopoulos, Gavin Wood
– This book covers the basics of Ethereum and how to build smart contracts and distributed applications (DApp), as well as the fundamentals of the Solidity language and practical coding.

2. ‘Solidity Programming Essentials: Your Hands-On Guide to Building Decentralized Web3 System Applications Security Secrets That Protect Your Smart Contracts from Hacks and Exploits’.

3. ‘Blockchain Applications: A Hands-On Approach’.
Authors: Arshdeep Bahga, Vijay Madisetti
– Describes a wide range of smart contracts and blockchain application cases, also dealing with Ethereum and Hyperledger implementations.

4. 『A Systematic Literature Review on Blockchain-based Smart Contracts: Platforms, Applications, and Challenges』

Multi-agent systems
1. ‘Multi-Agent Systems: An Introduction to Distributed Artificial Intelligence’.
Author: Jacques Ferber
– Systematically explains the theory and architecture of multi-agent systems (MAS). Fundamental content on distributed AI.

2. ‘An Introduction to MultiAgent Systems’.
Author: Michael Wooldridge
– Standard textbook covering basic concepts and advanced topics in agent-based systems.

3. ‘Agent-Based and Individual-Based Modelling’.
Authors: Steven F. Railsback, Volker Grimm
– Describes practical simulation modelling methods. Strengths in agent-based applications.

4. ‘Multiagent Systems: Algorithmic, Game-Theoretic, and Logical Foundations’.
Authors: Yoav Shoham, Kevin Leyton-Brown
– Approaches multi-agent systems from algorithmic, game-theoretic and logical foundations.

5. ‘Intelligent Agents and Multi-Agent Systems: Theoretical and Practical Aspects’.
Authors: Michael Luck, Ronald Ashri, Mark d’Inverno
– Balances theory and application in intelligent agents and MAS.

Integration areas: smart contracts x multi-agent systems
1. ‘Multi-Agent Systems and Blockchain: Results from a Systematic Literature Review’

2. ‘Decentralised Autonomous Organisations and Multi-Agent Systems’.
– Description: discusses the design and algorithms of DAOs (Decentralised Autonomous Organisations) and Multi-Agent Systems. In particular, the relationship with the implementation of smart contracts is analysed.