In some instances, cans of formula were being sold with the instructions in the wrong language for the women being targeted.
A formula ψ is a substitution instance of a formula φ if there is a substitution σ such that when applied to φ gives ψ, that is, if σ = ψ.
Notice that it is always possible to choose substitution instances of a pair of formulas so that the sets of their propositional variables are disjoint, because formulas are finite objects.
In all of these instances, a formula or set of criteria must dictate how many shares are to be bought or sold, at what price and on what dates.
Interestingly, an LTL formula can be seen as an instance of a QFLTL formula obtained by abstracting the constants appearing in the formula by new variables y∈ℝ q.
Thus, as the ratio of number of clauses (m) to number of prepositional variables (n) increases, random instances of 3-SAT progress from formulae which are generally satisfiable through to formulae which are generally not satisfiable, with an apparent sharp threshold being crossed when m/n ∼ 4.2.
In classical logic and in positive free logic any substitution instance of a valid formula (or form of inference) is itself a valid formula (or form of inference).
Consider, for example, the formula t=t, where t is empty, which is an instance of the open formula x=x.
So, in what follows, one should remember that whereas we can interpret the atomic formula Fx to mean either that x exemplifies the 1-place relation (i.e., property) F or that x falls under the concept F, Frege would understand such formulas as instances of functional application.
Thus not every substitution-instance of a stratified formula is stratified.
