What does floating operations mean in this context?

[Mattjd]

Reading about a memristor emulator. One of the features is "floating operations" I am not quite sure what this means.

3.3.2. Floating operation. In many memristor emulators,
input and output signals are given with voltages from the
ground. To use a memristor emulator in wide application
areas, it needs to have a floating operation. This floating
feature is achieved with the current conveyor, denoted as
CC0. With the architecture in figure 3, input voltage can be
applied between the V+ and V? terminals, which is the
floating operation.

[mikerj]

It simply means that the input voltage does not need to be referenced to ground in this case. Two input terminals are provided (V- and V?, is that a typo?), and only the difference in potential between the terminals is important.

[Mattjd]

It simply means that the input voltage does not need to be referenced to ground in this case. Two input terminals are provided (V- and V?, is that a typo?), and only the difference in potential between the terminals is important.

Okay. The next sections talks about the differences in the connection terminals for connectability. The requirement that the current going in must the same going out.

3.3.3. Connectability to other devices. To be a part of a
circuit, the memristor emulator has to be connectable to other
devices. To have connectability, the same current as the input
current must appear at the output terminal of the memristor
emulator, and the voltage at the input terminal of the
memristor emulator should be the sum of the memristor
emulator’s voltage and the voltage of the other device. The
former feature is realized with the current conveyor, CC0,
where resistances RC and RT are set to be equal. By applying
the same voltage as that of RT at the y terminal of the current
conveyor, the same current as the input current, iin, flows from
the x terminal and at the output (terminal z). This feature is
built with the analog voltage adder, U5, and a buffer, U4.