【PDDL语法学习】 了解领域文件（Domain）第四篇

​原文地址：https://planning.wiki/ref/pddl22/domain
推荐通过原文了解更多没有翻译到位的内容。

简介

PDDL2.2的域语法向域添加了非常小的更改。但是，与对PDDL的任何更新一样，它引入了新的 requirements，但惟一的新语法是派生谓词，谓词的定义方式与 actions 的定义方式类似，并且在域文件的同一节中定义。

先引入一个简单的实例：

(define
    (domain railways)
    (:requirements :derived-predicates :timed-initial-literals)
    (:types
        train station - object
    )
    (:predicates
        (train-not-in-use ?t - train)
        (train-has-guard ?t - train)
        (train-has-driver ?t - train)
        (train-usable ?t - train)
    )
    (:functions

        ... - omitted

    )
    (:durative-action MOVE-TRAIN

        ... - omitted

    )
    (:derived (train-usable ?t - train)
        (and
            (train-has-guard ?t)
            (train-has-driver ?t)
        )
    )
    (:derived
        ... - omitted
    )
)

内容

• Requirements
• Deeived Predicates
• Timed Initial Literals

Requirements

(:requirements <requirement_name>)

PDDL2.2在PDDL语法中添加的Requirements。

• :derived-predicates
• :timed-initial-literals

1、Derived Predicates:

(:derived <predicate_name> <logical_expression>)

派生谓词是通过命名派生结果的谓词来声明的，并通过计算逻辑表达式来计算值。
注意，派生谓词的声明类似于actions，因为派生谓词的每个声明都使用 :derived关键字。

(:derived (train-usable ?t - train)
    (and
        (train-has-guard ?t)
        (train-has-driver ?t)
    )
)

上面的例子指定了火车只有在有火车和司机的情况下才可用。

2、Timed Initial Literals：

(:requirements :timed-initial-literals)

允许在定义Problem时使用定时初始字面值。

(:init
	; 火车在step=10/sec=10的时候处于空闲状态，其中的数值设置由规划器默认设置为时间还是步骤
	(at 10 (train-not-in-use t1)) 

References

• PDDL - The Planning Domain Definition Language, [Ghallab, M. Howe, A. Knoblock, C. McDermott, D. Ram, A. Veloso, M. Weld, D. Wilkins, D.]
• PDDL2.1: An Extension to PDDL for Expressing Temporal Planning Domains, [Fox, M. Long, D.]
• PDDL2.2: The Language for the Classical Part of the 4th International Planning Competition[Edelkamp, S. Hoffmann, J.]
• PDDL Examples
• OPTIC - Optimising Preferences and Time Dependent Costs

​

标签：PDDL,Domain,requirements,派生,derived,train,谓词,第四篇
来源： https://blog.csdn.net/dongbox_/article/details/121679226