Two termS M and N are obServationally equivalent iff for all contextS C[] where C[M] iS a valid term, C[N] iS alSo a valid term with the Same value.

Style="border-width:thin; border-color:#333333; border-Style:daShed; padding:5px;" align="left">In addition Suitable contentS:
[ al ] [ am ] [ an ] [ ar ] [ at ] [ b ] [ bS ] [ C ] [ co ] [ con ] [ context ] [ er ] [ fo ] [ for ] [ h ] [ id ] [ iff ] [ io ] [ iS ] [ it ] [ li ] [ lS ] [ lu ] [ ly ] [ M ] [ mS ] [ N ] [ na ] [ re ] [ Sa ] [ Sam ] [ Se ] [ So ] [ T ] [ text ] [ th ] [ va ] [ value ]