. . . . . . . "In modal logic, the modal depth of a formula is the deepest nesting of modal operators (commonly and ). Modal formulas without modal operators have a modal depth of zero."@en . "Profondit\u00E0 modale"@it . . . . "3597"^^ . . "25312886"^^ . . . . "In modal logic, the modal depth of a formula is the deepest nesting of modal operators (commonly and ). Modal formulas without modal operators have a modal depth of zero."@en . . "Modal depth"@en . . . "927633149"^^ . . .