Mattern: vector time that preserves distributed causal order

What is recorded here?

Mattern formulated vector-valued logical time that captures potential causal order and concurrency, connected possible time vectors with the lattice of consistent cuts, and described distributed debugging applications. A distributed system has no single clock that reveals what every process knows. Ordinary logical clocks ensure that an earlier causal event has a smaller timestamp, but smaller scalar timestamps can also belong to unrelated events. Vector time keeps one component for each process. A process advances its own component and merges received knowledge using componentwise maxima. Comparing two complete event vectors then distinguishes potential causal ancestry from concurrency in the fully instrumented message-passing model. Mattern also connects consistent global cuts with a lattice of possible vector times, providing a language for reasoning about distributed state. The inspected edited author reprint explicitly acknowledges that Colin J. Fidge independently suggested and discussed vectors of logical clocks. It also credits earlier version vectors for detecting conflicting file copies. This record covers Mattern's specific formulation and cut-lattice account, rather than granting him sole invention of every vector-clock idea. The original Fidge paper remains a separately identified source needing full-body inspection. A causal path means that influence was possible; it does not prove that an earlier event actually caused a later outcome, recover wall-clock timing or reveal every direct message edge.

Source-linked catalogue note. A detailed explanatory guide has not yet been prepared for this entry.

Scientific scope

The timestamp construction uses a specified distributed-process and message model. Vector comparisons represent causal partial order under correct updates; concurrent events need not receive a unique total order. Metadata grows with the process model, and clocks do not establish wall-clock time, truth or Sybil-resistant identity. Later dynamic/compact versions are separate.

Read the original work

• Mattern, Virtual Time and Global States of Distributed Systems — edited author-posted version
• Mattern author institutional bibliography: original1989 proceedings and1994 reprint

This English explanation is an editorial reading view. It does not replace the complete original work or certify its science.

People and systems

Friedemann Mattern

Source-listed contributors to this scoped work. Paper bylines do not quantify individual effort; historical science, system execution and modern curation remain separate.