Grammars and Languages

1
Grammars and Languages

• Objectives
• Tell the difference between a natural language
  and a formal language
• Give a definition of a formal language, and give
  a definition for a simple formal language
• Create a grammar using the Backus-Naur form
• Describe one use of BNF grammars

• Outline
• Natural vs. Formal Languages
• Grammars
• BNF form
• Speech Recognition
• Chapter 11, Section 1

2
Natural languages

• English Grammar Set of rules to determine
  whether a combination of words is valid.
• The dog barks loudly
• Green runs vinegar squishy
• Blue red loud dogs ponder slowly

3
Natural Language

• Snytax the structure of a statement
• Semantics the meaning of a statement
• Natural languages syntax much too complicated
• Formal Language specified by a well-defined set
  of rules of syntax.

4
Formal Language Example

• Sentence Noun Phrase (NP) followed by a Verb
  Phrase (VP)
• Noun Phrase an Article followed by Adjective
  followed by a noun.
• Noun Phrase an Article followed by a noun.
• Verb Phrase A verb followed by an adverb.
• Verb Phrase A verb.
• Article a, the Adjective purple,
  emaciated, jovial
• Noun grape, brick, goose Verb
  flails, falls, flaps
• Adverb wildly, sadly

5
Formal language example

• New Rule
• Adjective An adjective followed by an adjective.

6
Phrase-Structure Grammars

• Vocabulary (alphabet) V is a finite set of
  symbols
• Sentence (word) over V is a string of finite
  length of elements of V
• Language a subset of all sentences (words) over
  all possible sentences.

7
Backus-Naur Form

• ltidentifiergt ltlettergt ltidentifiergtltlettergt
  
• ltidentifiergtltdigitgt
• ltlettergt a b c d e ... x y
  z
• ltdigitgt 0 1 2 3 4 5 6 7
  8 9

8
Backus Naur Form

• Which of the following are valid Identifiers
• tmp
• x
• ham43
• 4loop
• 2
• the_quick_7_brown_4837_foxes

9
Voice-Based Control
NCSAs Translator Voice Recognition Software
http//woodall.ncsa.uiuc.edu/dbock/Tools/Translato
r/
10
HapticControl
11
Commands

• ltrootgt hard to ltdirectiongt
• easy to ltdirectiongt
• steady as she goes
• sound the alarm.
• ltdirectiongt starboard port.

12
Advanced command structure for Control

• ltrootgt hard to ltdirectiongt
• easy to ltdirectiongt
• steady as she goes
• set throttle to ltlevelgt
• ltclutch_statusgt the clutch
• set transmission to ltgeargt
• set heading to ltbearinggt
• set position to point ltpoint_namegt
• honk the horn
• sound the alarm
• call for help
• good job.
• ltdirectiongt starboard port.
• ltlevelgt low medium high.
• ltclutch_statusgt engage disengage.
• ltgeargt reverse forward low forward high.
• ltbearinggt north south east west
  northeast northwest southeast southwest.
• ltpoint_namegt alpha bravo charlie.

13
HCI Example

• ltrootgt ltgogt ? ltgo_modegt
• ltstart_stopgt ltpickinggt
• ltstopgt
• ltselectgt ltselect_whatgt ?
• ltshow_getgt information about that
  object.
• ltgogt go.
• ltgo_modegt forward backward faster
  slower.
• ltstart_stopgt start stop.
• ltpickinggt pick mode picking.
• ltstopgt stop.
• ltselectgt select.
• ltselect_whatgt that one that.
• ltshow_getgt show get.