/English agreement/
/start/
t;

/rules/
[r:this,num:,per:,case:] :: =n[case:]< d -k[num:sg,per:3]<;
[r:boy,num:sg,per:3,case:] :: n[num:sg,per:3]<;
walk :: =d v;
[r:prs,num:,per:] :: =>v +k[case:str]< t;