The notion of equations [versus constraints]

Explanations based on constraints

1D [systems based on] constraints

[Excluded blocks in] dynamical systems theory

2D [systems based on] constraints

Numbering scheme [for 2D constraints]

Identifying the 171 patterns [that satisfy 2D constraints]

Checking [tilings with] constraints

Representing repetitive [2D] patterns

Searching for patterns [that satisfy constraints]

Undecidability [for 2D constraints]

NP completeness [for 2D constraints]

Non-periodic pattern [forced by 2D constraint]

Other types of [2D] constraints

Relation to 2D cellular automata

Relation to 1D cellular automata

Correspondence systems [as constraints]

Formal languages [and constraints]