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# Graph Theory 101 (WebEngDus17)

Graph Theory 101 – putting theory into practice
Graphs are everywhere! Learn the core basics of graph theory and see how this can be applied in a number of practical, every-day use cases.

5min talk from ELI5 series (explain me like I'm five)
Presentation consists of slides and interactive flip-chart session (not uploaded here) July 20, 2017

## Transcript

1. Graph Theory 101 by @another_clue
putting theory into practice

2. graph theory
discrete mathematics
2

3. No, not charts/diagrams!
3

4. G=(V,E)
ordered set G = (V,E)
V: set of vertices/nodes/points
E: set of edges/connections/lines/arrows/arcs
4

5. properties
empty
trivial
edgeless
… 5

6. attributes
vertex labels
edge weights
types
… 6

7. putting into Practice
7

8

V = people
E = friends (undirected)
Amy befriended with Bob
9

is an undirected graph
10

11

V = accounts
E = follower (directed)
YourName follows @webengdus
12

is a digraph (directed graph)
13

14. git
14

15. git
V = objects (commits, tags etc.)
E = object references
v1.0.0 refs #abc
15

16. git
is a DAG (directed acyclic graph)
16

17. sat nav
17

18. sat nav
V = cities
18

19. sat nav
multigraph (parallel edges, loops)
shortest path? algorithms and heuristics
19

20. Conclusions
20

21. graphs are everywhere!
21

22. care about edges? use a graph!
22

23

24. plenty of graph databases
24

25. Do you need a graph database?
25

26. // thank you!
26
@another_clue – https://lueck.tv/

27. 27
Exercise

28. 28
@WebEngDus
Exercise

29. 29
@another_clue
@WebEngDus
Exercise

30. 30
@clue
@another_clue
@WebEngDus
Exercise

31. 31
@clue
@another_clue
@WebEngDus
@graphp
Exercise

32. 32
@clue
@another_clue
@WebEngDus
@graphp
YOU!
Exercise

33. More…
33

34. static analysis
34

35. static analysis
V = functions
E = functions invocation
main() calls run() calls print()
35

36. static analysis
digraph
remove vertices with indegree=0
36