# Enumerate over mathmode items with partial curly brace

I'm trying to create an enumerated list that has four items in math mode, three of which are enclosed by a large right curly brace.

I found a semi-solution that uses the multirow package, but it works for only two items in the curly brace section.

I'm hoping to find a solution that involves the enumerate or enumitem packages, because I want the ability to change the labeling of the enumeration to roman numerals. Some answers use the tikzmark package, but I was hoping for something less of a big machine.

If you have any elegant solution to my problem outside the ideas I have, thats fine too!

Here is a MWE for you to test (ignore most of the preamble):

\documentclass[12pt]{report}
\usepackage[margin=1in]{geometry}
\usepackage[most]{tcolorbox}
\usepackage{amsmath , amsthm , amssymb, mathtools}
\usepackage{multirow}
\ExplSyntaxOn

\NewDocumentCommand{\betternewtcbtheorem}{O{}mmmm}
{
\newtcbtheorem[#1]{#2inner}{#3}{#4}{#5}
\NewDocumentEnvironment{#2}{O{}}
{
\keys_set:nn { hushus/tcb } { ##1 }
\hushus_tcb_begin:nVV {#2inner} \l__hushus_tcb_title_tl \l__hushus_tcb_label_tl
}
{
\end{#2inner}
}
\cs_if_exist:cF { c@#5} { \newcounter{#5} }
}

\cs_new_protected:Nn \hushus_tcb_begin:nnn
{
\begin{#1}{#2}{#3}
}
\cs_generate_variant:Nn \hushus_tcb_begin:nnn { nVV }
\keys_define:nn { hushus/tcb }
{
title .tl_set:N = \l__hushus_tcb_title_tl,
label .tl_set:N = \l__hushus_tcb_label_tl,
}

\ExplSyntaxOff

\betternewtcbtheorem[number within = chapter]{dfn}{Definition}%
{
enhanced,
before title = {\stepcounter{dfn}},
colback=blue!10,
colframe=blue!35!black,
fonttitle=\bfseries,
top=3mm,
attach boxed title to top left={xshift = 5mm, yshift=-1.5mm},
boxed title style = {colback=blue!35!black}
}{dfn}

\newcommand\rdot[1][.5]{\mathbin{\vcenter{\hbox{\scalebox{#1}{$\bullet$}}}}}
\begin{document}

\begin{dfn}[title=Subring]
A subring $S$ of a ring $R$ is a subgroup that is closed under multiplication. That is $S\subset R$ if $\forall a,b \in S$, $\begin{tabular}{ll} (1) a+b\in S \quad (closure under +) & \multirow{3}{*}{{\LARGE \}} S is a subgroup} \\ (2) 0\in S \\ (3) -a\in S \\ (4) a\rdot b\in S (closure under \rdot ) \end{tabular}$
\end{dfn}

\end{document}


• A shameful "solution" in the absence of anything else: \multirow{3}{*}{{\scalebox{1}[4]{\}}} $S$ is a subgroup}
– Ivan
Feb 5 at 0:27
• You might do that with the \listliketab and bigdelim packages (Unrelated: needless to load amsmath if you load mathtools). Feb 5 at 0:32

Set the construction using a nested tabular: The first 3 rows with a \left....\right\} with the last row as part of the outer/main tabular.
\begin{dfn}[title=Subring]
A subring $S$ of a ring $R$ is a subgroup that is closed under multiplication. That is $S\subset R$ if $\forall a,b \in S$, $\begin{tabular}{ l } \left.\kern-\nulldelimiterspace \begin{tabular}{@{} l @{}} (1) a + b \in S \quad (closure under +) \\ (2) 0 \in S \\ (3) -a \in S \end{tabular}\right\} S \text{ is a subgroup} \\ (4) a \rdot b \in S (closure under \rdot) \end{tabular}$