Status: IN
Palindrome problems serve as the canonical exemplar of the full Counter-to-pipeline reduction chain: Counter construction from string (algebraic construction), frequency extraction (algebraic measurement), parity reduction (algebraic projection), and threshold aggregation (streaming accumulation) — exercising every layer of the hash-then-stream pipeline within a single problem class and demonstrating how Counter's algebraic completeness flows through the pipeline architecture.
Palindromes exercise every layer from Counter algebra through hash preprocessing to streaming output
Depends on (SL): palindrome-instantiates-hash-then-stream, counter-is-complete-multiset-algebra