Higher-order closure schemes

Some of the difficulties associated with gradient diffusion are alleviated by further manipulation of the basic conservation equations to create equations for the time rate of 

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In what is one of the few examples of utilization of a higher order sigmatropic hydrogen shift in the synthesis of complex molecules, Eschenmoser, in studies directed toward the synthesis of Vitamin B12, found that an antarafacial [1,16] H-shift could be utilized to effect closure of secocorrin 63 to corrin 65 (Scheme 16)31. An intermediate biradical... 

The same problem is compounded in architectural descriptions, where DDD uses recursive networks of streams to model synchronous hardware. Animation of streams in Scheme is done using function closures and continuations to implement call-by-need behavior. Neither of these higher-order objects can be expressed directly in Nqthm, nor can nonterminating function systems. 

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