Apollonian networks are chordal maximal planar graphs, or equivalently planar 3-trees. The susceptibility (or equivalently the permittivity) is frequency dependent. Light output as a function of infrared wavelength (or equivalently, wavenumber). Affine space is usually studied as analytic geometry using coordinates, or equivalently vector spaces. For any , there exists a unique integer such that , or equivalently . In photography, ND filters are quantified by their optical density or equivalently their f-stop reduction. Tube amplifiers are usually heavier than an equivalently powered transistor amplifier. Fermions are classified according to how they interact (or equivalently, by what charges they carry). A googolplex is the number 10, or equivalently, 10. Setting formula 32 yields formula 33 or equivalently, formula 34. The primary aim of these tests are to ensure all students are assessed equivalently. Carbonic acid is a chemical compound with the chemical formula (equivalently&colon; OC(OH)). "x" such that&colon;formula 50or equivalently,formula 51This is easily arranged.