1. In en.wikipedia.org/wiki/Channel\_access\_method, 

> 
> A channel-access scheme is based on a multiplexing method, that allows several data streams or signals to share the same
>  communication channel or physical medium. Multiplexing is in this
>  context provided by the physical layer.
> 
> 
> multiplexing also may be used in **full-duplex point-to-point
>  communication between nodes in a switched network**, which should
>  not be considered as **multiple access**
> 
> 
> 

Why "multiplexing also may be used in full-duplex point-to-point
communication between nodes in a switched network, **which should
not be considered as multiple access**"?
2. In en.wikipedia.org/wiki/Media\_access\_control, 

> 
> Examples of **shared physical media** are ..., and h**alf-duplex point-to-point links**. 
> 
> 
> 

Are "shared physical media" the same as "multiple access media"?
Why are "half-duplex point-to-point links" "shared physical media"?

Thanks.