ontology - How to keep rule head as null using Protege swrl tab -

i trying capture conflict using swrl rules. learned swrl support rules empty head(consequent). protege not allow defining such rules. dummy example of trying achieve is

person(?x)^hasson(?x,?y)^hasdaughter(?x,?y)-> 

meaning not possible person can linked same individual both hasson , hasdaughter properties. if not possible in protege, please guide me on how achieve alternatively.

the rule body can empty, not imply contradiction, in intentions; interpreted rule not applying. specs here.

if understand intent correctly, after can achieved creating 2 classes: define exact cardinality restriction of 0 hasson , exact cardinality restriction of 0 hasdaughter, assign these classes range of hasdaughter , hasson respectively.

this way, stating a hasson b , a hasdaughter b cause inconsistency.