Logic - What does a half T mean in logic? TLDR nevermind I'll include a screenshot;
I've looked for the symbol everywhere, it wasn't even found via wikipedia:
https://en.wikipedia.org/wiki/List_of_logic_symbols
It also wasn't in the list of mathematical symbols: https://en.wikipedia.org/wiki/List_of_mathematical_symbols
There's a section called 'advanced and rarely used logical symbols' in the wiki page for logic, and it's not even there. So that is officially the point at which I give up.
I don't mean the symbols for True, T. The stem of the T by the way, remains untouched, it's just that the left side is 'cut off'.
Also, I would copy and paste the damn thing, but it's always added in via a super special way, and it just turns out like this: f  Γ. So yeah.
 A: In Sequent Calculus discussions, capital greek letters such as $\Gamma, \Delta, \Sigma,$ and $\Pi$, are often used as symbols for finite sets of first order predicate logic formula.   (Pronounced "gamma", "delta", "sigma", and "pi".)
https://en.wikipedia.org/wiki/Sequent_calculus#Inference_rules
In this case the rule of implication introduction, means that "if some set of formula and $A$ entails $B$, then that set of formula entails that $A$ implies $B$." $${\begin{array}{rcl}\Gamma, A & \vdash & B \\\hline \Gamma&\vdash&A\to B\end{array}}{\small{\to}\mathsf I}$$
A: As others have pointed out, your "$T/2$" is the upper-case Greek letter gamma.
For the record, as I can't find it anywhere else on MSE, here is the Greek alphabet as supported by MathJax and $\LaTeX$ and used throughout mathematics. The format is:
$$
\begin{array}{llll}
\mbox{Name} & \mbox{Upper-case glyph} & \mbox{Lower-case glyph} & \mbox{Variant glyph (if any)}.
\end{array}
$$
Use \Name for the upper-case letter and \name for the lower-case letter. Letters with a superscript 1 (like $A^1$) look like Latin letters, so they aren't useful as mathematical symbols and $\LaTeX$ and MathJax don't have a macro for them (you could try to defend notation like $H(H)$ by claiming that the second $H$ is an upper-case eta, but this is probably not going to make you popular $\ddot{\smile}$). Letters with a superscript 2 (like $\varphi^2$) are a variant lower-case form: use \varname for these.
$$
\begin{array}{llll}
\mbox{Alpha} & A^1 & \alpha \\
\mbox{Beta} & B^1 & \beta \\
\mbox{Gamma} & \Gamma & \gamma \\
\mbox{Delta} & \Delta & \delta \\
\mbox{Epsilon} & E^1 & \epsilon & \varepsilon^2 \\
\mbox{Zeta} & Z^1 & \zeta \\
\mbox{Eta} & H^1 & \eta \\
\mbox{Theta} & \Theta & \theta \\
\mbox{Iota} & I^1 & \iota \\
\mbox{Kappa} & K^1 & \kappa \\
\mbox{Lambda} & \Lambda & \lambda \\
\mbox{Mu} & M^1 & \mu \\
\mbox{Nu} & N^1 & \nu \\
\mbox{Xi} & \Xi & \xi \\
\mbox{Omicron} & O^1 & o^1 \\
\mbox{Pi} & \Pi & \pi \\
\mbox{Rho} & P^1 & \rho \\
\mbox{Sigma} & \Sigma & \sigma & \varsigma^2 \\
\mbox{Tau} & T^1 & \tau \\
\mbox{Upsilon} & \Upsilon & \upsilon \\
\mbox{Phi} & \Phi & \phi & \varphi^2 \\
\mbox{Chi} & X^1 & \chi \\
\mbox{Psi} & \Psi & \psi \\
\mbox{Omega} & \Omega & \omega
\end{array}
$$
Corrections and comments welcomed.
