Language Model Grammar Conversion Wesley Holland, Julie Baca, Dhruva Duncan, Joseph Picone Center for Advanced Vehicular Systems Mississippi State University XMLABNF BNF IHD BNF JSGF

Page 1 of 10 Language Model Grammar Conversion Speech Recognition Acoustic Model Maps audio data to words or phonemes Language Model Specifies order in which a sequence of words or phonemes is likely to occur Described using grammar

Page 2 of 10 Language Model Grammar Conversion Grammar Specifications Backus-Naur Form (BNF) Augmented BNF (ABNF) JSpeech Grammar Format (JSGF) Speech Recognition Grammar Specification (SRGS) ISIP Hierarchical Digraph (IHD) ::=ab* =a(b)*; a b BNF ::=aB ::=bB ::=ε ABNFJSGF XML-SRGSIHD

Page 3 of 10 Language Model Grammar Conversion Conversion Design Goals JSGF ↔ IHD XML-SRGS ↔ IHD Determination of equivalence Grammar minimization Final Architecture XML JSGF ABNFBNFIHD

Page 4 of 10 Language Model Grammar Conversion JSGF/XML-SRGS → ABNF JSGF → ABNF Trivial Similar in syntax and structure to ABNF XML-SRGS → ABNF Harder than JSGF Different in syntax and structure from ABNF Requires enumeration of certain repeat attributes ::=(ab)|(abab) XML-SRGS a b ABNF ::=abab(ab)* a b

Page 5 of 10 Language Model Grammar Conversion JSGF/XML-SRGS → ABNF XML-SRGS → ABNF (continued) Different weighting mechanisms (weight and repeat-prob attributes) a b c d

Page 6 of 10 Language Model Grammar Conversion ABNF → BNF Normalized BNF Consists of rules of the following formats: (RULE_NAME)::=(TERMINAL),(NON_TERMINAL) (RULE_NAME)::=(NON_TERMINAL) (RULE_NAME)::=ε ABNF BNF 1.Break rule into multiple rules at each top-level alternation. Recurse on each rule. 2.For each concatenation, Kleene star, or Kleene plus, extract a set of left symbols and a set of right symbols. 3.For n left symbols and m right symbols, create n x m connecting rules. ABNF → BNF Complicated Accomplished using a recursive algorithm that extracts sets of normalized BNF rules from a set of ABNF rules

Page 7 of 10 Language Model Grammar Conversion BNF ↔ IHD Each arc translates to a normalized BNF Terminals correspond to nodes; concatenations correspond to arcs RS→R0R3→C,R3 RS→R1R3→C,RT R0→A,R3RT→ε R1→B,R3 BNF Nodes 1: A 2: B 3: C Arcs (S,1)(2,3) (S,2)(3,3) (1,3)(3,T) IHD

Page 8 of 10 Language Model Grammar Conversion BNF → JSGF/XML-SRGS Rule-by-rule Trivial =aB; =b*; a b <ruleref special= “NULL”/> BNF ::=aB ::=bB ::=ε JSGF XML-SRGS

Page 9 of 10 Language Model Grammar Conversion Software Tools ISIP Network Converter Console tool to perform conversions to and from arbitrary grammar formats ISIP Network Builder Java-based graphical tool to design grammars as finite state machines Can exports grammars to JSGF, XML-SRGS, ABNF, BNF, and IHD ISIP Language Model Tester Console tool for testing of grammars Can generate valid sentences in a given grammar Can parse sentences and determine if accepted by a given grammar.

Page 10 of 10 Language Model Grammar Conversion Minimization Happens in BNF Iterate over rule set, merging redundant rules Rules can be merged if the non terminal of both rules reference the same terminal Example: