Hello. The entire symbol \(\displaystyle f(Z_1, Z_2, Z_3, … Z_n)\) is function notation, and it represents a single number. That number is called the 'function output'. This particular function has been named \(\displaystyle f\). In function notation, the function's 'inputs' are listed inside the parentheses. The function's output depends upon its inputs; in other words, the value of symbol \(\displaystyle f(Z_1, Z_2, Z_3, … Z_n)\) depends upon the numbers inside the parentheses.

Yes, your guess is correct. The number \(\displaystyle f(Z_1, Z_2, Z_3, … Z_n)\) is multiplied by the number \(\displaystyle P_o\), and that result is assigned to symbol \(\displaystyle S\).

They have not provided a definition for function \(\displaystyle f\), so even if somebody were to give you values for each threat level \(\displaystyle Z_i\) and for the defense potential \(\displaystyle P_o\) you would still not be able to calculate a value for \(\displaystyle S\). In other words, the equation that they have provided is only a symbolic statement. Without the function definition or an example using actual numbers, we don't know what arithmetic they might be doing with their numbers \(\displaystyle Z_1, Z_2, Z_3, … Z_n\) and \(\displaystyle P_o\).

It could be that they have not actually determined a definition, yet. That equation might be a

*general statement* that is intended only to express something like, "We would objectively quantify 'security state' as a function of multiple, subjective 'threat levels' and a 'defense potential' parameter", without actually having done it.

You can google keywords

function notation, to find lessons, videos and examples of how the notation is defined and used. Cheers

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