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The vNFT created by Solv is dedicated to adding computability to the non-homogeneous pass NFT, that is, while retaining the powerful personalized description ability of NFT, it makes "quantity" the core attribute of its NFT, enabling it to support computation. Computable NFT is a "super NFT" compatible with ERC721. It also has the advantages of ERC20 and ERC721. It is a general non-monetary digital asset description protocol and can be widely used in digital artworks, digital publications, digital tickets, and standardized virtual goods. Description and representation can also become an ideal protocol for mapping offline physical goods to the chain.

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Figure 1. Positioning of Computable NFT, vNFT and Solv Vouchers in the entire token technology system

Computable NFT is the latest development of the token technology system and a new field with great research and application value. The Solv team has taken the lead in developing a reference implementation of computable NFT on Ethereum, which has been verified in the Solv Vouchers product. Since the computable NFT implemented by Solv is called Voucher, we call this token standard vNFT before the related proposal is standardized.

vNFT is a platform-independent digital asset standard. It has been implemented on Ethereum and will soon be implemented on chains such as BSC and Polygon. In the future, it is also planned to be implemented on various mainstream public chains such as Solana, NEAR, Polkadot and Ethereum L2 realized.

Readers who have studied digital assets will not be difficult to see that the combination of computability and NFT will stimulate great innovation. We will not only disclose all standard documents according to the requirements of EIP, but also fully open source the reference implementation code at the right time. We welcome digital asset innovators from all over the world to join us in promoting the application of this technology.

This article briefly introduces the basic idea, design scheme and application significance of computable NFT. For the sake of precise expression, the following conventions are made for the terminology:

Computable NFT (Computational Non-fungible Token) refers to NFT with computability.

Voucher refers to a specific computable NFT that follows the vNFT standard. Anyone can create a voucher for a specific application based on vNFT, such as a voucher representing a bill of lading, a voucher representing a certificate of title, a voucher representing an investment share, and so on. In the absence of misunderstanding, this article sometimes uses voucher to represent a specific token.

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1 NFT is not uncomputable

The main advantage of Homogeneous Token (FT) is that it can be calculated, so it is suitable for expressing purely numerical objects such as currency and points. The main advantage of non-homogeneous token (NFT) lies in its strong descriptive ability, and each NFT can have different properties and contents. The so-called strong descriptive ability, in other words, high efficiency. If there are 100 different items to be described by tokens, if FT technology is used, such as the ERC20 standard, then 100 different ERC20 contracts must be written and 100 different ERC20 tokens issued.

To make an analogy, in ERC20, in order to produce 100 different products, 100 different factories must be built first, and then each factory only produces one product, so the efficiency is naturally very poor. In NFT, you only need to create an ERC721 contract, then cast 100 different NFTs, and write different data content in each NFT. This is like building only one factory to produce 100 different products, which is naturally more efficient.

The current NFT is mainly created based on the ERC721 protocol. Each NFT created by this protocol is unique, neither of the same kind nor divisible. It's like this factory has a strange temper. Each product can only produce one product, and cannot produce more than one. Therefore, ERC721 has a huge flaw, that is, it cannot be calculated.

Why do you say it cannot be calculated? In ERC721, any two NFTs cannot be added together, not even addition, and naturally other calculations cannot be performed.

Due to the influence of preconceived ideas, many people take its incomputability for granted when talking about NFT, and even take it as the essential attribute and source of value of NFT. Many people think that since it is meaningless to add an apple to a pear, then of course one NFT cannot be added to another NFT, let alone more advanced calculations such as quantitative multiplication.

But in fact, after a little in-depth thinking, you will realize that NFT is not necessarily incomputable.

Taking works of art and collectibles as examples, Da Vinci's "Mona Lisa" and Yan Zhenqing's "Nephew's Manuscript" are naturally unique, but prints, posters, stamps, star cards, rubbings of rubbings and other items can be unique. Is a limited edition, not unique. For example, a set of stamps is limited to 1,000 sets, and any two sets of them, although strictly speaking, are different, but the differences between them are so slight that we can ignore their differences and look at them abstractly. into is exactly the same.

In other words, this kind of ignoring and abstraction is essentially a process of re-homogenization. We transform a group of heterogeneous and different items into homogeneous items that are conceptually the same. Since it is homogeneous, it can be calculated in many scenarios. One of the most prominent scenarios is price calculation. For example, if the price of a set of stamps is 200 yuan, then the price of another set of stamps of the same edition will be 200 yuan. Few would charge a different price for the two sets of stamps because they differ by a few pixels. Similarly, if the current price of a three-year treasury bill with a face value of 100 yuan is 90 yuan, then the current price of 10 treasury bills with the same face value should be 900 yuan, and no one will give different valuations because one of the treasury bills has a folded corner .

It can be seen that the incomputability of NFT is by no means a matter of course. For a large class of NFTs, computability will bring great convenience to their practical applications.

• Which NFTs are computable? There are mainly some:

• Digital representation of standard products

• Various documents and certificates

• Digital Financial Tickets and Standardized Contracts

• Limited release digital content

• Shareable Certificate of Entitlement

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2 Abstraction and classification are the basis of NFT computability

No two leaves are exactly alike, and no two apples are alike. As long as you don't enter the microscopic world, there are only one completely different thing after another in this world. We can never add one apple to another, nor can we arrive at the concept of "two apples". Therefore, when Lu Xun said that of the two trees outside the wall, one is a jujube tree and the other is also a jujube tree, this is not literature.

Fortunately, human beings have a remarkable cognitive ability, which is abstraction and classification. The so-called abstraction is actually purposefully ignoring the special features of an item, but emphasizing the commonality between it and certain other items, and based on this commonality, these items are placed under a certain concept and classified into one category. It is precisely because of this ability that people can develop concepts such as "apple", "leaf", "tiger", and "jujube tree", and under certain scenarios, it is allowed to perform sum calculations between similar items. When we say "two apples", we are actually abstracting two items that are classified as the same kind into exactly the same thing, eliminating the differences between them, performing a "re-homogenization", and then making a single The operation of adding one equals two can create the concept of "two apples".

However, ERC721, as the current mainstream NFT standard, one-sidedly emphasizes the uniqueness of each NFT, and does not provide a standard way to abstract and classify NFT. This is the fundamental reason why ERC721 NFT is not computable, and it is also the starting point for the innovation of computable NFT.

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3 Basic idea of ​​vNFT

vNFT is a specific standard for computable NFT. Its purpose is to add computability to NFT. Specifically, it allows the creation of a large number of similar NFTs in batches in vNFT. This is like the factory of vNFT, which can produce unique products or mass-produce a product according to requirements, with the best flexibility and efficiency.

vNFT is designed based on the following three basic ideas:

First, take "quantity" as the core attribute of vNFT;

Third, it is compatible with ERC721.

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3.1 Quantity as the core attribute of vNFT

Computable NFTs are different. A computable NFT must contain a quantitative attribute, which is the basic reason why it can support mathematical calculations. To do this, we put quantity as a core property in the vNFT. For example, if you use a vNFT to represent your digital business card, and its quantity is 100, it means that it is not a business card, but a collection of 100 business cards. Of course, this number can also be 1.

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Figure 2. vNFT uses quantity as a core attribute

It can be seen that a vNFT can be either a single and unique NFT, or the sum of several vNFTs of the same type. For example, a bond with a face value of 100 yuan can be regarded as the sum of 100 bonds with a face value of 1 yuan. A bill of lading containing 30 pieces of a product of a certain model can be regarded as the sum of 30 bills of lading for a single product. Solv sets the "quantity" as a first-class attribute in the vNFT, which is juxtaposed with the ID information of the vNFT, thus making the above addition possible. In other words, the addition of two vNFTs is actually a kind of merger, which is the operation of adding the quantitative attributes of the two while keeping other attributes unchanged. This is the fundamental starting point of computability.

The inverse operation of addition is subtraction, so with the attribute of quantity, a direct consequence is that it is possible to split the vNFT into zeros. A vNFT can be split into two parts, as long as the sum of the number attributes of the two vNFTs is equal to the number attribute of the original vNFT. For example, in vNFT, a bond token with a face value of 100 yuan can be split into two bonds with a face value of 20 yuan and 80 yuan respectively. In fact, in the Solv Vouchers platform, users can not only split, but also partially transfer. Currently, NFT sharing and splitting are hot topics, and there are some feasible technical solutions, but they are all cumbersome. In vNFT, it is very natural and simple to support NFT sharing, splitting and partial transfer.

The quantity attribute in vNFT is very flexible in practice, and can express the quantity of shares, as well as various measures such as area, length, weight, price, etc. The vNFT standard allows developers to impose various restrictions on these quantities, such as the maximum amount, the minimum amount, whether it can be split, the smallest unit of split, etc., to meet the needs of various application scenarios.

3.2 SLOT mechanism

SLOT is the core innovation of vNFT, so it must be explained with a little ink.

SLOT in English means "slot". In modern electronic equipment, a socket is a standardized adapter interface. For example, there are several standard slots on the motherboard of a computer. No matter which manufacturer produces the board, as long as it follows the relevant standards and can be inserted into the slot, it can work normally. Different types of boards produced by different manufacturers are of course different from each other, but under the abstraction and unification of slots, their differences are ignored, but are abstracted into identical, homogeneous standard parts.

As an example. Suppose we create a vNFT category for a book warehouse to represent the book delivery order, for example, use a list to represent the delivery right of 100 books. The representation of this monad in vNFT is as follows:

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What role can SLOT play? A SLOT is a subset of attributes in a vNFT. Suppose a SLOT delineates three attributes (book number, warehouse number, book title), which means that as long as two vNFTs are exactly the same in these three attributes, they can be classified into one category.

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Figure 4. A subset of SLOT attributes in a book bill of lading"ISBN 978-7-5217-2263-5", "For example, we see two vNFTs, both of which contain these three attributes, and both of them are ("，"Beijing Haidian Warehouse 3"), then no matter what other attributes these two vNFTs have, and no matter whether their other attributes are the same, we can think that these two vNFTs belong to the same SLOT, that is, they belong to the same category. Thus they can be summed. When they are summed, the two vNFTs are merged into one, and the new vNFT holds the values ​​of these two properties, summing the values ​​of its quantity property.

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Figure 5. Addition of two book delivery slips vNFT

It can be seen that SLOT is an abstract classification mechanism, which allows us to deliberately ignore certain aspects of things, and classify different things into the same category based on some commonalities. Once classified, "re-homogenization" can be performed to perform numerical calculations.

It is worth pointing out that the SLOT mechanism actually allows individual vNFTs to personalize themselves, that is, to declare that they do not belong to a certain category. In practice, the designer of a voucher can put some special attributes in the SLOT, which is convenient for a specific vNFT to assign values ​​to these special attributes to make itself "stand out" and become a class of its own. In other words, if SLOT is a "rehomogenization" mechanism, then these special properties in SLOT are an "anti-rehomogenization" mechanism. This shows the flexibility of the SLOT mechanism. This is a relatively advanced usage of the SLOT mechanism, which will not be expanded in detail here.

3.3 Compatible with ERC721

Computable NFTs can be implemented in a number of ways. For example, ERC1155 is also a computable NFT implementation standard in a sense, but there are many differences in the design of vNFT, one of the important differences is that vNFT is compatible with ERC721, and each vNFT is also a ERC721. Readers familiar with object-oriented programming can easily understand that vNFT can be regarded as a derivative of ERC721, so if an application supports ERC721, it already supports vNFT. In contrast, ERC1155 started from scratch, completely creating a brand-new token standard, and each application needs to write codes to support ERC1155. There is no doubt that this backward compatibility of vNFT greatly reduces the threshold for its application. In practice, all kinds of vouchers created by Solv can be directly managed in various NFT wallets, and can also be circulated in NFT markets such as OpenSea, reflecting the advantages of this design choice.

The vNFT is equivalent to a smart factory. It can produce unique products or mass-produce similar products. It also allows channels and users to customize these products, and when adding new products, it does not require others to do structural work. Adjustment. Obviously, compared to ERC20, ERC721 and ERC1155, vNFT has the greatest flexibility and dynamics.

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4 Application scenarios of vNFT

Computable NFT is actually a homogenization of non-homogeneous tokens, so it not only has the abstraction and computability of homogeneous tokens, but also has the flexibility and description capabilities of NFTs. The best balance. In the field of overseas digital asset research, some people refer to this kind of pass as "semi-homogeneous pass", which is attracting more and more attention.

• The following uses vNFT as an example to explore some possible applications:

• Use vNFT to make digital business cards, star cards, admission tickets, stamps and other limited-issue items;

• Use vNFT to represent shareable and shared asset title certificates, such as land or house title certificates,

• Use vNFT to represent certificates with natural quantitative characteristics, such as bills of lading, exchange vouchers, coupons, point cards, etc.;

• Use vNFT to represent the ownership certificate of virtual real estate with area attributes;

• Use vNFT to represent virtual items in the game;

• Use vNFT to make exquisite functional tickets, which not only have specific functions in the system, but also are artistic and collectible;

• Use vNFT to create limited-edition encrypted artworks that collectors can sign and comment on;

The above list is far from exhausting the application scenarios of vNFT. There is no doubt that computable NFT can play a key role in almost all fields of the future digital economy, and vNFT, as the native standard of computable NFT, will be widely used.

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5 Progress of vNFT

The Solv team began to study computable NFTs in October 2020, formally established the technical idea in December, completed the design and reference implementation of vNFTs in the first quarter of 2021, and officially launched the Solv Vouchers Ethereum mainnet on June 17, 2021. Solv Vouchers itself represents the token share with time-locked release, compatible with ERC721, and can be split, merged, partially transferred, and linear operations such as addition and multiplication can be performed, and each voucher has a well-designed appearance, becoming a Distinctive digital assets.

The innovation of Solv Vouchers has been recognized by many international excellent DeFi projects and protocols. At present, more than 20 DeFi projects have established strategies with Solv, including DODO, Parsiq, Bounce, NAOS Finance, Ankr, Saffron Finance, Impossible Finance, etc. The affirmation from peers fully proves the value and effectiveness of vNFT and Solv Vouchers innovation.