Findel is a composable DSL for financial derivatives that can be executed on the blockchain. The language is simple and expressive enough to express complex derivatives. However, compared to its competitors, Findel does not guarantee that contracts progress properly. There is no default refund mechanism, and the economic enforcement is not handled by the language itself. Given the immutability of the blockchain, more caution should be taken in order to avoid undesired situations.

In this paper, we address the formal verification of financial derivatives written in Findel. We define a formal semantics of Findel in Coq and we test it against the existing Findel test suite. We enrich our semantics with means to interactively formalise and prove properties about Findel contracts. The goal is to avoid mistakes in Findel contracts that may have a negative impact (e.g., stuck contract executions, money losses). The derived infrastructure is used to certify non-trivial contract examples that cover the most common types of derivatives (forwards/futures, swaps, options).

Findel是用于金融衍生产品的可组合DSL，可在区块链上执行。该语言简单易表达，足以表达复杂的派生词。但是，与竞争对手相比，芬德尔不能保证合同会正常进行。没有默认的退款机制，经济执行也不由语言本身处理。考虑到区块链的不可变性，应格外小心，以避免出现意外情况。

在本文中，我们讨论用Findel编写的金融衍生产品的形式验证。我们在Coq中定义了Findel的形式语义，并针对现有的Findel测试套件进行了测试。我们通过交互式地形式化和证明Findel合同的属性的手段来丰富我们的语义。目的是避免Findel合同中可能产生负面影响的错误（例如，合同执行卡滞，资金损失）。派生的基础结构用于证明涵盖最常见衍生产品类型（期货/期货，掉期，期权）的非平凡合同示例。