Trust Contracts

OWL and TAL to expand expressive power
while retaining decidability to support secure
and precise execution of contracts.

BOScoin aims to use the Owlchain technology which consists of the Web Ontology Language(OWL) and Timed Automata Language(TAL). This architecture is designed to expand expressive power while retaining decidability to support secure and precise execution of contracts. These Owlchain based contracts on the BOScoin blockchain are called Trust Contracts.

[Trust Contract Blockchain]

Features Bitcoin Ethereum OWL-chain (BOScoin)


Current : PoW
Future : Casper (?)


-History revision mechanism

Soft and hard forks

Current : Soft and hard forks
Future : Block revisions in case of temporary network isolation

Block revisions in case of temporary network isolation




Open with constraint
(min 10,000BOS)

Block Confirmation Time

10 minutes

15 seconds

5 seconds (target)

Block Size

1 MB



Maximum Transaction

100 KB

Dynamic based on gas limit


Transaction Speed

7 tx/sec

25 tx/sec

1,000 tx/sec (target)


Bitcoin, plus tokens such as provied by Omni Layer

Ether, plus tokens that can be issued by contracts


Governance System



Commons budget, Proposal, Voting

Smart Contracts :
-Computational Power

Stack-based language with few instructions

Turing complete

Timed Automata Model



Not Decidable, using instruction fee (gas)


-Runtime Architecture

Script runs on Bitcoin Core, Libbitcoin and other native implementations

Ethereum Virtual Machine implemented on multiple platforms

OWL inference Engine on multiple platform

-Programming Language

Bitcoin Script

Solidity, Serpent, LLL and any other languages that get implemented on the EVM



The Owlchain’s hierarchy was designed as a general blockchain model to accommodate multiple ontology models. The Owlchain combines the feature of the Inference Engine and Consensus protocol to handle the Trust Contract.

  • OWL (Web Ontology Language)

    OWL is a standard language developed to support the Semantic in the web. OWL 2 standardization was introduced to accommodate the use of the new profile concept in an attempt to solve the performance problem that was problematic in the previous version. There are three different types of OWL 2 Profile. In the case of a complex expression(TBOX), it is possible to obtain optimized ontology results by selecting the OWL 2 EL profile. In other case, where there are lots of individuals to declare, selecting OWL 2 QL profile can result in creating a better ontology database. Owlchain supports a user to select an appropriate OWL 2 profile to configure the blockchain. The user shall select the profile according to the type of ontology database that they plan to build

  • TAL (Timed Automata Language)

    OWL, which is a language for knowledge representation(KR), does not support the computational power needed for processing the blockchain. In the case of Ethereum, the computing capacity required for processing Smart Contract is resolved by implementing the turing complete Ethereum virtual machine(EVM). However, the method of using virtual machines will result in the undecidability of the blockchain, which is not resolved in terms of security aspects of the blockchain network. We use the Timed Automata Language execution environment in a manner that considers the computational power and decidability. The timed automata ensures that all programs base on the timed automata is guaranteed to operate in a finite time limit. Timed Automata Language(TAL) is a programming language designed to support the computational functionalities within a range that do not impair the integrity of the blockchain. Instead of supporting turing completeness, TAL provides the computational power through a finite automata model.

Contract Comparison

Features Smart Contracts
Ricardian Contracts
Trust Contracts
Programming Language

LLL, Serpent, Solidity

Ricardian Contract + purefun ctions

Owlchain (OWL+TAL)


Undecidable with gas(fee)

(3rd party evaluation)


Blockchain Type




Consensus Algorithm




Contract Inference



OWL Reasoning