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Our primary motivation is the comparison of two different traditions used in implicit computational complexity to characterize the class FPTIME of the polynomial time computable functions. On one side, FPTIME can be captured by Intuitionistic Light Affine Logic (ILAL), a logic derived from Linear Logic, characterized by the structural invariant Stratification. On the other side, FPTIME can be captured by Safe Recursion on Notation (SRN), an algebra of functions based on Predicative Recursion, a restriction of the standard recursion schema used to define primitive recursive functions. Stratification and Predicative Recursion seem to share common underlying principles, whose study is the main subject of this work.

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Mathematician. He studied mathematical logics and logical foundations of computer science at the University of Torino, Italy.

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