Intra-step Interaction

For a while it seemed possible to pretend that all interaction between an algorithm and its environment occurs inter-step, but not anymore. Andreas Blass, Benjamin Rossman and the speaker are extending the Small-Step Characterization Theorem (that asserts the validity of the sequential version of the ASM thesis) and the Wide-Step Characterization Theorem (that asserts the validity of the parallel version of the ASM thesis) to intra-step interacting algorithms. 1 Why Intra-Step Interaction According to the Lipari guide [9], an abstract state machine interacts with the environment by means of external functions. “The computation steps of a program are supposed to be atomic at an appropriate level of abstraction. A computation step is hardly atomic if during that step the [ASM] queries an oracle and then, depending on the result, submits another query to the same or a different oracle. Thus it seems reasonable to forbid nesting of external functions. Indeed, the need to nest external f...

• Type: Conference
• Year: 2004
• Where: ASM
• Authors: Yuri Gurevich
• Keywords: Abstract State Machine, ASM 2004, External Functions, Intra-step Interaction, Microbiology