Some Programming Languages for Logspace and Ptime

We propose two characterizations of complexity classes by means of programming languages. The first concerns Logspace while the second leads to Ptime. This latter characterization shows that adding a choice command to a Ptime language (the language WHILE of Jones [1]) may not necessarily provide NPtime computations. The result is close to Cook in [2] who used "auxiliary push-down automata". Logspace is obtained through a decidable mechanism of tiering. It is based on an analysis of deforestation due to Wadler in [3]. We get also a characterization of NLogspace. We propose a contribution to the program of Jones [1]: "We maintain that Computability and Complexity theory, and Programming Language and Semantics [...] have much to offer each other, in both directions." ; we give characterizations of complexity classes by means (of restrictions) of programming languages. The present contribution belongs to a largely wider program (see [4

• Type: Conference
• Year: 2006
• Where: AMAST
• Authors: Guillaume Bonfante
• Keywords: AMAST 2006, Characterization, Complexity Classes, Programming Languages, Software Engineering