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The EVM’s physical instantiation can’t be described in the same way that one might point to a cloud or an ocean wave, but it does exist as one single entity maintained by thousands of connected computers running an Ethereum client.

The Ethereum protocol itself exists solely for the purpose of keeping the continuous, uninterrupted, and immutable operation of this special state machine. It's the environment in which all Ethereum accounts and smart contracts live. At any given block in the chain, Ethereum has one and only one 'canonical' state, and the EVM is what defines the rules for computing a new valid state from block to block.

Some basic familiarity with common terminology in computer science such as bytes(opens in a new tab)↗, memory(opens in a new tab)↗, and a stack(opens in a new tab)↗ are necessary to understand the EVM. It would also be helpful to be comfortable with cryptography/blockchain concepts like hash functions(opens in a new tab)↗ and the Merkle tree(opens in a new tab)↗.

The analogy of a 'distributed ledger' is often used to describe blockchains like Bitcoin, which enable a decentralized currency using fundamental tools of cryptography. The ledger maintains a record of activity which must adhere to a set of rules that govern what someone can and cannot do to modify the ledger. For example, a Bitcoin address cannot spend more Bitcoin than it has previously received. These rules underpin all transactions on Bitcoin and many other blockchains.

While Ethereum has its own native cryptocurrency (Ether) that follows almost exactly the same intuitive rules, it also enables a much more powerful function: smart contracts. For this more complex feature, a more sophisticated analogy is required. Instead of a distributed ledger, Ethereum is a distributed state machine(opens in a new tab)↗. Ethereum's state is a large data structure which holds not only all accounts and balances, but a machine state, which can change from block to block according to a pre-defined set of rules, and which can execute arbitrary machine code. The specific rules of changing state from block to block are defined by the EVM.

(opens in a new tab)↗ Diagram adapted from Ethereum EVM illustrated(opens in a new tab)↗

The EVM behaves as a mathematical function would: Given an input, it produces a deterministic output. It therefore is quite helpful to more formally describe Ethereum as having a state transition function:

Given an old valid state (S) and a new set of valid transactions (T), the Ethereum state transition function Y(S, T) produces a new valid output state S'

In the context of Ethereum, the state is an enormous data structure called a modified Merkle Patricia Trie, which keeps all accounts linked by hashes and reducible to a single root hash stored on the blockchain.

Transactions are cryptographically signed instructions from accounts. There are two types of transactions: those which result in message calls and those which result in contract creation.

Contract creation results in the creation of a new contract account containing compiled smart contract bytecode. Whenever another account makes a message call to that contract, it executes its bytecode.

The EVM executes as a stack machine(opens in a new tab)↗ with a depth of 1024 items. Each item is a 256-bit word, which was chosen for the ease of use with 256-bit cryptography (such as Keccak-256 hashes or secp256k1 signatures).

During execution, the EVM maintains a transient memory (as a word-addressed byte array), which does not persist between transactions.

Contracts, however, do contain a Merkle Patricia storage trie (as a word-addressable word array), associated with the account in question and part of the global state.

Compiled smart contract bytecode executes as a number of EVM opcodes, which perform standard stack operations like XOR, AND, ADD, SUB, etc. The EVM also implements a number of blockchain-specific stack operations, such as ADDRESS, BALANCE, BLOCKHASH, etc.

(opens in a new tab)↗ Diagrams adapted from Ethereum EVM illustrated(opens in a new tab)↗

All implementations of the EVM must adhere to the specification described in the Ethereum Yellowpaper.

Over Ethereum's nine year history, the EVM has undergone several revisions, and there are several implementations of the EVM in various programming languages.

Ethereum execution clients include an EVM implementation. Additionally, there are multiple standalone implementations, including:

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* Associate of Coudert Brothers, UIC Building, 5 Shenton Way, Singapore 0106, Member of the Texas Bar (not licensed to practice Singapore law).

** The Arbitration Act 1953 (as amended 1980) is published in International Handbook on Commercial Arbitration, Supp. 4, Nov. 1985, as an annex to "National Report Singapore."

(1) Tan Boon Chiang, President of the Industrial Arbitration Court, Singapore, "Opening Address at the Proceedings of the Conference on New Concepts in Arbitration" held on 14 October 1981, published by the Singapore Institute of Arbitrators, December 1981.

(2) Craig, Park, Paulsson, International Chamber of Commerce Arbitration (Oceana Publications Inc. 1984) Appendix 1, page 13, (Table 5).

(3) Id. at page 16, (Table 7).

(4) Id. at page 7, (Table 4).

(5) Section 5 of the Civil Law Act, Chapter 30, Singapore Statutes, provides that in commercial law matters the law to be applied by Singapore courts is the same as the relevant law in England except in cases where a different "provision is or shall be made by any law having force in Singapore".

(6) See for example, Loke Hong Kee (S) Pte. Ltd. and United Overseas Land Ltd. 1 M.L.J. 108 (O.C.J., 1978); M.L.J. 5 (C.A., 1979); 2 M.L.J. 83 (P.C., 1982) where, in Singapore court proceedings relating to an arbitration, English cases and commentaries are cited extensively and a question is appealed to the Privy Counsel in London.

(7) The Rules of the Supreme Court, 1970 (hereinafter the "Rules") are arranged into 93 orders (hereinafter each an "Order"). Each Order in turn regroups several rules (hereinafter each a "Rule ").

(8) It is unclear whether incorporation of a fine print boilerplate arbitration clause in standard conditions would meet the requirement of a written agreement.

(9) See discussion at Chap. VI.4, infra.

(10) This language follows that of the exclusion agreement printed in the Arbitration Rules of the London Court of International Arbitration. See J. Steyn, "National Report England", Yearbook Vol. VIII (1983) pp. 3-33 at p. 9.

(11) Wong Wai Cheng v. Attorney-General of Singapore, 1 M.L.J. 59 (O.C.J., 1978); 1 M.L.J. 131 (C.A., 1979).

(12) 1 M.L.J. 59 (O.C.J., 1978).

(13) On appeal, 1 M.L.J. 131 (C.A., 1979), the arbitral award was set aside because the arbitrator erred in his understanding of the case.

(14) But see Section 28B(3)(b) regarding the effect of an exclusion agreement on the issue of fraud; and discussion at Chap. VI.4, infra.

(15) The rules of the Singapore Institute of Arbitrators do not provide for the Institute to serve as appointing authority for arbitrations to be conducted under the UNCITRAL Rules.

(16) See for example Kian Hong Holdings Private Ltd. and Ohbayashi-Gumi Ltd., 2 Singapore High Court Judgments 151 (1982). This broad view of a "question of law" is particularly significant in view of the date of the case: well after the 1980 Amendment.

(17) See discussion at Chap. VI.3A, infra.

(18) See discussion at Chap. IV.3, supra, as to the means of compelling the testimony of a recalcitrant party in Singapore.

(19) But see discussion of Section 18(l) at Chap. III.2, supra.

(20) However, if the award is to be enforced in Singapore it will have to be translated into English. For enforcement. See Chap. V.10, infra.

(21) 1 M.L.J. 114 (O.C.J., 1981).

(22) Exclusion agreements and their relation to the issues of court review of actions by an arbitrator beyond the scope of his jurisdiction and of fraud will be dealt with in Chap. VI.4.

(23) However, no cases relating to enforcement of such an award on agreed terms were found among reported cases.

(24) See discussion at Chap. V.3, supra.

(25) "Taxation of costs" means review by an officer of the court to allow, modify or disallow costs which have been awarded by a tribunal. Appeal to a judge is possible if a party is dissatisfied with the decision of the officer of the court. See, also Kian Hong Holdings Private Ltd. v. Ohbayashi-Gumi Ltd., 2 Singapore High Court Judgments 151 (1982), Where it was held that the claimants were "to get 70% of the taxed cost of the Arbitration proceedings as well as of this application. Cost for two counsel allowed in the hearing of this application".

(26) See discussion at Chap. III.2 and Chap. V.4, supra.

(27) Orders 45 and 46 of the Rules set forth the means of enforcement and execution of judgments or orders.

(28) Section 20 provides for the conversion of awards into judgments by leave of court. Thus, reference is made herein to "judgments and awards" or "awards" although the text of Orders 45 and 46 refer to "judgments".

(29) Order 46, Rule 4(l).

(30) Order 46, Rule 7.

(31) Karthigesu, M., "The Settlement of Commercial Disputes in Singapore", 2 M.L.J. xi, xv.

(32) Section 28(4).

(33) See this Chapter under 3, infra.

(34) 1 M.L.J. 32 (C.A., 1962).

(35) Pursuant to Paragraph 6 of the First Schedule to the Arbitration Act.

(36) Section 17(2).

(37) 2 M.L.J. 99, 100 (O.C.J., 1978).

(38) 1 M.L.J. 185 (C.A., 1972).

(39) See Chap. V.4, supra, regarding pleas as to arbitrator's jurisdiction.

(40) For a sample text of an exclusion agreement, see Chap. II.1, supra.

(41) Section 28B(l). See also discussion at Chap. II.1, supra.

(42) Section 28B(3).

(43) See, for example, Loke Hong Kee (S) Pte. Limited v. United Overseas Land Limited, 2 M.L.J. 83 (P.C., 1980), appeal to the Privy Council in London following statement of certain points of law involved in an arbitration to the Singapore High Court and appeal to the Singapore Court of Appeal.

(44) Judicial Committee Act 1966, Singapore Statutes, Vol. I, Ch. 8.

(45) Arbitration (International Investment Disputes) Act, Singapore Statutes, Vol. I, Ch. 17.

(46) For a detailed discussion of this topic see Gopal, G., "Rules of the International Centre for Settlement of Investment Disputes", 1 M.L.J. cxviii.

(48) Press release of 8 November 1985.

(49) Hereinafter the "Commonwealth Judgments Act".

(50) In 1980, the Commonwealth Judgments Act had been extended to Australia, Brunei, Ceylon, Hong Kong, India (except the States of Jammu and Kashmir), Malaysia, New Zealand, Pakistan, Papua/New Guinea and the Windward Islands. See Martin, supra at xiii.

(51) 2 M.L.J. 5 (O.C.J., 1971).

(52) Commonwealth Judgments Act, Section 3(l).

(53) Commonwealth Judgments Act, Section 3(2).

(54) Hereinafter the "Foreign Judgments Act".

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One useful approach to finding the MVUE begins by finding a sufficient statistic for the parameter. is independent of θ, for all θ ∈ Λ, where t = T(y). i.e., if we know T(Y ), then there is no need to know θ. The following Theorem provides a necessary and sufficient condition for having a sufficient statistic.

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