Accessing parent's namespace

[NotionCommotion]

Is it possible to have a class access another class it its parent directory without using a fully qualified name?  While the following script is not valid, it is how I would have thought it would be done should it be possible.  If it is not possible, I expect there is a good reason why one would not want to do so, and would appreciate your thoughts why that is so.  Thanks

// src/PrimaryTopic/SubTopic/SubSubTopic/ParentClass.php
namespace PrimaryTopic\SubTopic\SubSubTopic;
class ParentClass {}

// src/PrimaryTopic/SubTopic/SubSubTopic/Child/ChildClass1.php
namespace PrimaryTopic\SubTopic\SubSubTopic\Child;
class ChildClass1 extends ..\ParentClass {}

// src/PrimaryTopic/SubTopic/SubSubTopic/Child/ChildClass2.php
namespace PrimaryTopic\SubTopic\SubSubTopic\Child;
class ChildClass2 extends ..\ParentClass {}

 

[requinix]

Not like that, no.

use PrimaryTopic\SubTopic\SubSubTopic\ParentClass;

class ChildClass1 extends ParentClass {