Concrete-vs-Abstract Responsibility Split
Kind: algorithm
Record: algorithms:concrete-vs-abstract-responsibility-split
Canonical: Algorithms
Closure: Dependencies in load order
Partition the family's behavior into what is invariant across every member (the topology preserved under substitution) and what varies per member (the novelty); the invariant set becomes the concrete base, the variant set becomes the abstract seam. The concrete/abstract boundary is derived from the evidence, not read off a fixed lifecycle vocabulary — so the split holds for any paradigm, not only OOP class lifecycles.
Listed in Algorithm contracts, after Base-Class Candidate Selection and before Template Method Lifecycle.