Update

math.md

@@ -18,6 +18,7 @@ TODOOOOOOOOOOOOOOOOO
 - **[linear algebra](linear_algebra.md)**: aka "vectors and matrices", essential in many fields such as [graphics](graphics.md) and [machine learning](machine_learning.md).
 - **[calculus](calculus.md) and differential equations**: just essential for advanced math and many fields (graphics, machine learning, electricity, physics, any optimization, ...).
 - **theoretical [computer science](compsci.md)**: [computational complexity](computational_complexity.md) (very important), [computability](computability.md), [formal languages](formal_language.md), computational models ([automata](automaton.md), [Turing machines](turing_machine.md), ...), ...
+- **[graph theory](graph.md)**: generally useful tools, especially important e.g. in networks or indexing structures in [databases](database.md).
 - **number and set theory**: sets of numbers (natural, rational, real, imaginary, ...), [prime numbers](prime.md) (important e.g. for [cryptography](cryptography.md)), ...
 - **discrete math**: basic structures such as [groups](group.md) and [fields](field.md) and their properties.
 - **[signal processing](signal_processing.md)**: [Fourier transform](fourier_transform.md) and other integral transforms (important e.g. for [compression](compression.md) and analysis of signals), [aliasing](aliasing.md), filter theory, ...