Simplify $$$\left(\overline{A} \cdot \overline{B}\right) + \left(\overline{A} \cdot B \cdot \overline{C}\right) + \overline{A + \overline{C}}$$$

Apply de Morgan's theorem $$$\overline{x + y} = \overline{x} \cdot \overline{y}$$$ with $$$x = A$$$ and $$$y = \overline{C}$$$:

$$\left(\overline{A} \cdot \overline{B}\right) + \left(\overline{A} \cdot B \cdot \overline{C}\right) + {\color{red}\left(\overline{A + \overline{C}}\right)} = \left(\overline{A} \cdot \overline{B}\right) + \left(\overline{A} \cdot B \cdot \overline{C}\right) + {\color{red}\left(\overline{A} \cdot \overline{\overline{C}}\right)}$$

Apply the double negation (involution) law $$$\overline{\overline{x}} = x$$$ with $$$x = C$$$:

$$\left(\overline{A} \cdot \overline{B}\right) + \left(\overline{A} \cdot B \cdot \overline{C}\right) + \left(\overline{A} \cdot {\color{red}\left(\overline{\overline{C}}\right)}\right) = \left(\overline{A} \cdot \overline{B}\right) + \left(\overline{A} \cdot B \cdot \overline{C}\right) + \left(\overline{A} \cdot {\color{red}\left(C\right)}\right)$$

Rewrite:

$${\color{red}\left(\left(\overline{A} \cdot \overline{B}\right) + \left(\overline{A} \cdot B \cdot \overline{C}\right)\right)} + \left(\overline{A} \cdot C\right) = {\color{red}\left(\left(\left(B \cdot \overline{C}\right) + \overline{B}\right) \cdot \overline{A}\right)} + \left(\overline{A} \cdot C\right)$$

Apply the commutative law:

$$\left({\color{red}\left(\left(B \cdot \overline{C}\right) + \overline{B}\right)} \cdot \overline{A}\right) + \left(\overline{A} \cdot C\right) = \left({\color{red}\left(\overline{B} + \left(B \cdot \overline{C}\right)\right)} \cdot \overline{A}\right) + \left(\overline{A} \cdot C\right)$$

Apply the redundancy law $$$x + \left(\overline{x} \cdot y\right) = x + y$$$ with $$$x = \overline{B}$$$ and $$$y = \overline{C}$$$:

$$\left({\color{red}\left(\overline{B} + \left(B \cdot \overline{C}\right)\right)} \cdot \overline{A}\right) + \left(\overline{A} \cdot C\right) = \left({\color{red}\left(\overline{B} + \overline{C}\right)} \cdot \overline{A}\right) + \left(\overline{A} \cdot C\right)$$

Rewrite:

$${\color{red}\left(\left(\left(\overline{B} + \overline{C}\right) \cdot \overline{A}\right) + \left(\overline{A} \cdot C\right)\right)} = {\color{red}\left(\left(C + \overline{B} + \overline{C}\right) \cdot \overline{A}\right)}$$

Apply the commutative law:

$${\color{red}\left(C + \overline{B} + \overline{C}\right)} \cdot \overline{A} = {\color{red}\left(C + \overline{C} + \overline{B}\right)} \cdot \overline{A}$$

Apply the complement law $$$x + \overline{x} = 1$$$ with $$$x = C$$$:

$$\left({\color{red}\left(C + \overline{C}\right)} + \overline{B}\right) \cdot \overline{A} = \left({\color{red}\left(1\right)} + \overline{B}\right) \cdot \overline{A}$$

Apply the commutative law:

$${\color{red}\left(1 + \overline{B}\right)} \cdot \overline{A} = {\color{red}\left(\overline{B} + 1\right)} \cdot \overline{A}$$

Apply the dominant (null, annulment) law $$$x + 1 = 1$$$ with $$$x = \overline{B}$$$:

$${\color{red}\left(\overline{B} + 1\right)} \cdot \overline{A} = {\color{red}\left(1\right)} \cdot \overline{A}$$

Apply the commutative law:

$${\color{red}\left(1 \cdot \overline{A}\right)} = {\color{red}\left(\overline{A} \cdot 1\right)}$$

Apply the identity law $$$x \cdot 1 = x$$$ with $$$x = \overline{A}$$$:

$${\color{red}\left(\overline{A} \cdot 1\right)} = {\color{red}\left(\overline{A}\right)}$$