The **OACC** is a powerful online calculator devoted to provide estimations of algorithmic complexity (a.k.a. Kolmogorov-Chaitin complexity) (or $K$) and Algorithmic Probability for short and long strings and for 2-dimensional arrays better than any other tool, and estimations of Bennett's Logical Depth (or $LD$) for strings hitherto impossible to estimate with any other tool. These 3 measures constitute the most powerful and universal algorithmic measures of complexity. It uses a method (called $BDM$) based upon Algorithmic Probability, which is compatible with--but beyond the scope of--lossless compression algorithms that are so widely used to estimate $K$. Implementations of lossless compression are, however, entirely based upon Shannon entropy ($S$) (e.g. LZ, LZW, DEFLATE, etc) and thus cannot capture any algorithmic content beyond simple statistical patterns (repetitions).

In contrast, $BDM$ not only considers statistical regularities but is also sensitive to segments of an algorithmic nature (such as in a sequence like $12345...$), which $S$ and lossless compression algorithms would only be able to characterize as having maximum randomness and the highest degree of incompressibility. Moreover, unlike $K$ (thanks to the Invariance Theorem) both Entropy and Entropy-based compression algorithms **are NOT invariant** to language description and are therefore neither suitable nor robust as measures of complexity (the arguments and an example may be found here).

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**The OACC is a project developed by the following labs:**

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