As used in sections 12-345b to 12-345f, inclusive, the term “general power of appointment” means a power, whether created before or after May 24, 1972, which is exercisable in favor of the decedent, his estate, his creditors or the creditors of his estate, except that (a) a power to consume, invade or appropriate property for the benefit of the decedent which is limited by an ascertainable standard relating to the health, education, support or maintenance of the decedent shall not be deemed a general power of appointment; (b) a power of appointment created on or before October 21, 1942, which is exercisable by the decedent only in conjunction with another person shall not be deemed a general power of appointment; and (c) in the case of a power of appointment created after October 21, 1942, which is exercisable by the decedent only in conjunction with another person: (1) If the power is not exercisable by the decedent except in conjunction with the creator of the power, such power shall not be deemed a general power of appointment; (2) if the power is not exercisable by the decedent except in conjunction with a person having a substantial interest in the property subject to the power, which is adverse to exercise of the power in favor of the decedent, such power shall not be deemed a general power of appointment. For the purposes of this section a person who, after the death of the decedent, may be possessed of a power of appointment, with respect to the property subject to the decedent’s power, which he may exercise in his own favor shall be deemed as having an interest in the property and such interest shall be deemed adverse to such exercise of the decedent’s power; and (3) if, after the application of subdivisions (1) and (2), the power is a general power of appointment and is exercisable in favor of such other person, such power shall be deemed a general power of appointment only with respect to a fractional part of the property subject to such power, such part to be determined by dividing the value of such property by the number of such persons, including the decedent, in favor of whom such power is exercisable. For purposes of subdivisions (2) and (3), a power shall be deemed to be exercisable in favor of a person if it is exercisable in favor of such person, his estate, his creditors or the creditors of his estate.