He has also contributed to research on Message Sequence Charts ( MSC ), where it was shown that weak realizability is undecidable for bounded MSC-graphs and that safe-realizability is in EXPSPACE, along with other interesting results related to the verification of MSC-graphs.
42.
He has also contributed to research on Message Sequence Charts ( MSC ), where it was shown that weak realizability is undecidable for bounded MSC-graphs and that safe-realizability is in EXPSPACE, along with other interesting results related to the verification of MSC-graphs.
43.
Despite its initial plausibility, the identity theory faces a strong challenge in the form of the thesis of multiple realizability, first formulated by Hilary Putnam . [ 19 ] It is obvious that not only humans, but many different species of animal can, for example, experience pain.
44.
The emergence of similar behavioral outputs or psychological functions brought about by similar or identical brain structures in convergent evolutive lineages would provide some evidence against multiple realizability, since it is highly improbable that this would happen, if not for constrains on the type of physical system that can realize mental phenomena.
45.
The only way to really empirically test the thesis of multiple realizability would be to examine brain structures and determine whether some homoplasious " psychological processes or functions might be'constructed'from different material " and supported by different brain structures just as the flight capacities of bats and birds emerge from different morphophysiologies.
46.
Furthermore, constraining the mappings seems to require either consideration of the external behavior as in behaviorism, or discussion of the internal structure of the realization as in identity theory; and though multiple realizability does not seem to be lost, the functionalist claim of the autonomy of high-level functional description becomes questionable.
47.
For example, a realizer for the proposition " A implies B " is a computable function which takes a realizer for A, and uses it to compute a realizer for B . Observe that realizability models characterize realizers for propositions in terms of their visible behavior, and not in terms of their internal structure.
48.
In the case of propositional logic, it coincides with Howard's statement : the extracted lambda term is the proof itself ( seen as an untyped lambda term ) and the realizability statement is a paraphrase of the fact that the extracted lambda term has the type that the formula means ( seen as a type ).
49.
It is the link between logic and computation that is usually attributed to Curry and Howard, although the idea is related to the operational interpretation of intuitionistic logic given in various formulations by L . E . J . Brouwer, Arend Heyting and Andrey Kolmogorov ( see Brouwer Heyting Kolmogorov interpretation ) and Stephen Kleene ( see Realizability ).
50.
One common defence of multiple realizability in the literature, however, is that any such response which attempts to address the problem of the possibility of " generalized " multiple realizability must necessarily be so " local " and " context " specific in nature, referring exclusively to a certain token system of a certain structure-type at a certain time, that its reductions would be incompatible with even a minimally acceptable degree of generality in scientific theorizing.
