Query	    ::= Fetch | Assert | Retract | Infer
Assert	    ::= 'assert' Phrase 
Retract	    ::= 'retract' Phrase 
Infer	    ::= 'infer' Constraint 'when' Phrase
Fetch	    ::= 'fetch' ( Number? Type | Procedure ) Where Using?
Where	    ::= 'where'? Phrase
Using	    ::= 'using' Namespace ( ',' Namespace )*
Phrase      ::= Constraint ( Conjunction Phrase )*
Constraint  ::= Subject? Negation? Predicate Object
Conjunction ::= Disjoint | Conjoint
Negation    ::= 'not'
Disjoint    ::= ',' | 'and'
Conjoint    ::= 'or'
Subject	    ::= Variable | URI | Procedure
Predicate   ::= Identifier | '=' | '!=' | '<' | '>' | '<=' | '>=' | '~'
Object	    ::= Subject | Type | Literal
Type	    ::= URI
Literal	    ::= String | Number
String	    ::= '"' /.+?/ '"'
Number	    ::= /-?\d+(.\d+)*/
Procedure   ::= Identifier '(' Object ( ',' Object )* ')'
Namespace   ::= Identifier URI
Variable    ::= '?' Identifier 
Identifier  ::= /\w\S*/
URI	    ::= /\w+:\S+/