Coq：无法在环境中推断类型为 "nat" 的内部占位符：ev : nat -> Prop

Question

我正在尝试执行 Software Foundation 类的 IndProp.v，但我立即遇到错误

Set Warnings "-notation-overridden,-parsing,-deprecated-hint-without-locality".
From LF Require Export Logic.
From Coq Require Import Lia.

...

Inductive ev : nat -> Prop :=s
  | ev_0 : ev 0
  | ev_SS (n : nat) (H : ev n) : ev (S (S n)).
===============================================

Cannot infer an internal placeholder of type "nat" in environment:
ev : nat -> Prop

我遇到过一些错误，核心类型被之前书中定义的那些所掩盖，但以前没有见过这个错误？

前面的章节编译正确。

denis@dgecko:~/books/Volume1_LogicalFoundations> coqc --version
The Coq Proof Assistant, version 8.14.0
compiled with OCaml 4.13.1

Answer 1

:= 符号后有一个虚假的“s”。

Coq：无法在环境中推断类型为 "nat" 的内部占位符：ev : nat -> Prop

Coq: Cannot infer an internal placeholder of type "nat" in environment: ev : nat -> Prop

coq