The notion of equations [versus constraints]
Linear and nonlinear systems
Explanations based on constraints
1D [systems based on] constraints
1D cellular automata
[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]
Enumerating patterns
Non-periodic pattern [forced by 2D constraint]
Other types of [2D] constraints
Forcing nested [2D] patterns
Relation to 2D cellular automata
Relation to 1D cellular automata
Non-computable [2D] patterns
Tiling [problems]
Polyominoes
Ground states of spin systems
Correspondence systems [as constraints]
Sequence equations
Pattern-avoiding sequences
Formal languages [and constraints]
Diophantine equations
Matrices satisfying constraints
Finite groups and semigroups
Constraints on formulas
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