# Elements of an argument map
Argument maps are directed, non-hierarchical graphs consisting of nodes and edges connecting these nodes. The nodes are visualized as boxes and the edges are visualized as arrows.
There are three kinds of nodes in Argdown argument maps:
|Node type||What it looks like|
|Statement node||Visualized as round box with a thick colored border and white background.|
|Argument node||Visualized as round box with a colored background.|
|Group node (cluster)||Visualized as grey box containing other nodes.|
To learn more about the difference between statements and arguments, read the syntax sections about arguments in Argdown.
There are three edge colors in Argdown argument maps, representing the six different relations of Argdown:
- Green arrows visualize support and entail edges
- Red arrows visualize attack, contrary and contradiction edges
- Purple arrows visualize undercut edges
As you can see, green and red edges each can represent several types of relations. Which relation a green or a red edge represents depends on
- its source and target node,
- the arrow head
- if the arrow points in one or both directions
- and if you use Argdown in loose or strict mode.
|What you see in the map||What it means|
|Two statement nodes are connected by a green arrow.||Strict mode: The source entails the target. Loose mode: The source supports the target.|
|Two argument nodes or a statement and an argument node are connected by a green arrow.||The source supports the target.|
|Two statement nodes are connected by a red arrow with triangle arrow heads going in both directions.||Two statements (of two equivalence classes) are contrary to each other (strict mode).|
|Two statement nodes are connected by a red arrow with diamond arrow heads going in both directions.||Two statements (of two equivalence classes) are contradictory to each other.|
|A statement or an argument is connected to another statement or argument by a directed (one-way) red arrow.||The source attacks the target.|
|Two arguments or a statement and an argument are connected by a purple arrow.||The source undercuts the target.|
Note that there is no arrow representing equivalent statements. The reason behind this is that each equivalence class can only be represented by one statement in an Argdown argument map. However, if you must visualize equivalence relations in your map, you can define entailment relations between two statements going both ways. Just be aware that this will not automatically merge the two statements into the same Argdown equivalence class.