Computability and Complexity/Formal Languages/Chomsky Hierarchy/sample LBA inputs

= Sample LBA Inputs =

These examples are for use with the perl LBA emulator provided at the bottom of ../Context Sensitive Languages/. That page also contains a description of what a LBA is and how it works.

This machine accepts strings of the form $$\{a^{n}b^{n}c^{n}d^{n}|n \ge 0\}$$. Note that in this example, the input must be bounded by one "_" on each side as a tape delimiter.

start findA findB findC findD reset halt :Start State: start :Accept States: halt :alphabet: _ a b c d $ :tape bound: 1 0 :rules: start    _     findA     _     right findA    $     findA     $     right findA    a     findB     $     right findA    _     halt      _     left findB    $     findB     $     right findB    a     findB     a     right findB    b     findC     $     right findC    $     findC     $     right findC    b     findC     b     right findC    c     findD     $     right findD    $     findD     $     right findD    c     findD     c     right findD    d     reset     $     left reset    $     reset     $     left reset    a     reset     a     left reset    b     reset     b     left reset    c     reset     c     left reset    d     reset     d     left reset    _     findA     _     right

Some sample inputs: These accept: _ a a a b b b c c c d d d _

_ _

_ a b c d _

These reject: _ a a a b b b c c d d d _

_ a c _

_ a b b c c d d _

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