Inconstructible

A pattern is considered inconstructible (or unsynthesizable) if it has no glider synthesis, either as a matter of principle or in practice. Gardens of Eden are by definition inconstructible, but not every provably inconstructible pattern is a Garden of Eden (for example, unsynthesizable oscillator 1).

Patterns containing large amounts of space dust may be considered inconstructible in the practical sense despite not having been proven (and in fact not being) inconstructible in principle.