Update FOL-BC-Ask.md

misspelling corrected.

Author: RuedigerLunde

md/FOL-BC-Ask.md

@@ -4,20 +4,20 @@
 __function__ FOL-BC-ASK(_KB_, _query_) __returns__ a generator of substitutions  
  __return__ FOL-BC-OR(_KB_, _query_, { })  
 
-__generator__ FOL-BC-OR(_KB_, _goal_, _θ_) __yeilds__ a substitution  
+__generator__ FOL-BC-OR(_KB_, _goal_, _θ_) __yields__ a substitution  
  __for each__ rule (_lhs_ ⇒ _rhs_) __in__ FETCH-RULES-FOR-GOAL(_KB_, _goal_) __do__  
    (_lhs_, _rhs_) ← STANDARDIZE-VARIABLES((_lhs_, _rhs_))  
    __for each__ _θ_' __in__ FOL-BC-AND(_KB_, _lhs_, UNIFY(_rhs_, _goal_, _θ_)) __do__  
-     __yeild__ _θ_'  
+     __yield__ _θ_'  
 
-__generator__ FOL-BC-AND(_KB_, _goals_, _θ_) __yeilds__ a substitution  
+__generator__ FOL-BC-AND(_KB_, _goals_, _θ_) __yields__ a substitution  
  __if__ _θ_ = _failure_ __then return__  
- __else if__ LENGTH(_goals_) = 0 __then yeild__ _θ_  
+ __else if__ LENGTH(_goals_) = 0 __then yield__ _θ_  
  __else do__  
    _first_, _rest_ ← FIRST(_goals_), REST(_goals_)  
    __for each__ _θ_' in FOL-BC-OR(_KB_, SUBST(_θ_, _first_), _θ_) __do__  
      __for each__ _θ_'' in FOL-BC-AND(_KB_, _rest_, _θ_') __do__  
-       __yeild__ _θ_''
+       __yield__ _θ_''
 
 ---
-__Figure__ ?? A simple backward-chaining algorithm for first-order knowledge bases.
+__Figure__ ?? A simple backward-chaining algorithm for first-order knowledge bases.