Kiertoketju

Kiertoketju is a Finnish term that translates roughly as "circular chain" or "recirculation chain." It denotes a closed sequence of elements in which the output of one step becomes the input of the next, ultimately returning to the starting point. The concept is used across disciplines to describe cyclic structures or processes.

In mathematics and computer science, kiertoketju commonly refers to a cycle or closed loop in a graph, network, or state machine. A cycle starts at a node and, by traversing edges, returns to the same node without necessarily visiting every element; its properties are central to cycle detection, graph theory, and algorithm design.

In engineering and process industries, kiertoketju describes a closed-loop system. Materials, energy, or information circulate within a defined boundary, with the system designed to minimize waste and improve efficiency. Examples include water recirculation in cooling systems, feedback control loops in automation, and recycling loops in manufacturing.

In sustainability and economics, kiertoketju is used to discuss circularity or closed material loops within a system, such as nutrient cycles, product take-back schemes, and supply chains designed to reintroduce end-of-life materials into production.

Characteristics of kiertoketju include a defined boundary, a feedback mechanism, and potential for stability or oscillations depending on delays and gains in the loop. Challenges include managing delays, accumulation of errors, and ensuring robustness.