In my view, TOC is just the reflection of a fundamental concept - the weakest link (dominant constraint or bottleneck) decides the strength (throughput) of any chain. I agree that these are complementary and I believe these are REDUNDANT in some sense. For example when we are striving for creating "flow", indirectly we are working on the bottlenecks (constraints as per TOC) and variabilities(Six-Sigma).Without addressing the constraints and variabilities in the first place, we can not have "flow" or "takt" or "heart beat" of any value stream. Lean encompasses (inherent) concepts of TOC and Six-Sigma and more over brings out the much needed people and cultural aspects to drive and sustain lean as an operating system. Do we still really need TOC and Six-Sigma as standalone topics when Lean can address all of this in a much better way???

Mark, the debate on whether the 3 initiatives are really enemies or friends has been going on for sometime, since the time they have become popular. Although one gets weary about the coining of new buzzwords like "Lean six sigma" or "TLS", that should not deter us from understanding them better and looking for proper application of the same. So in that sense, I tend to agree with what is said in the article linked in your post. There definetly are areas where the 3 overlap, but there are also unique strong points for each. For example, in a Value stream analysis of a manufacturing line, if you realise that variations and rejects at one work center is preventing you from achieving 'takt' time, typically you would launch a 'kaizen' project to rectify it. Now this 'kaizen' could use six sigma techniques to achieve the goal. Six sigma being more statistically oriented will yield better measurable improvements as well as control. On the other hand, if only six sigma is used, it is typically applied to the value added activity(generally 15-20% of overall process). This dilutes the effect of the improvement on the overall outcome. Lean steps in here to increase the % of valuse added activity in the overall thereby boosting the six sigma impact. As for TOC and Lean, in my view, the constraint in TOC and the 'pacemaker' in Lean are basically the same concepts. Lean just additionally optimizes the 'pacemaker' output to market/customer requirement through 'takt' time, whereas TOC calls for maximizing the output from a constraint, till it is no longer one. Both however denounce 'local optimization' So in my view, if these 3 (T,L & S) are pieces of a jigsaw puzzle, and are dropped onto a process, they will more or less fall into place. And I would tend to agree with the article that T, L, S might be the preferred sequence of appliaction.