> Substitution is a ternary operation, involving three Patterns that we have differentiated by their sequential position in the shell-bracket notation.
is the primary mechanism for computation and for proof in algebraic systems.
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Vgl. zur begrifflichen Ausgangslage Körner, J., Simonyi, G., Trifference, Studia Scientiarum Mathematicarum Hungarica 30, 1995, S. 95–103.