<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><DIV></DIV><DIV>The left-hand side xymatrix represents a linear algebra augmented matrix, and so I would like to add brackets around it, that is "[" and "]" in the customary manner. But I need to be able to connect the two diagrams with arrows. I've tried several approaches, but I've run into four problems: </DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>(i) While xy can draw braces ( "{" and "}" ) and parentheses ( "(" and ")" ), it seems that it does not draw brackets. Is this correct? </DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>(ii) If xy cannot draw brackets, I would hope to use parentheses. But I have not been able to position the parentheses around the entire first xymatrix. How might I do this?</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>(iii) Related to (ii), if I try to group the xymatrix on the lhs using braces, I can't connect to the rhs with arrows. So I'm looking for a solution that will allow me to draw arrows from the xymatrix on the lhs to the one on the rhs.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>(iv) The xy parentheses I've been able to draw are pretty thick. How can I make them thinner?</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>The xy code I'm trying to use is below (I use the package ps4pdf, but I've not included that code here):</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>\def\determinantdiagram#1#2#3#4{%</DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>\xy%</DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>\xymatrix"*"@1@=0mm@M=0mm@R=.5mm@C=.5mm{#1}</DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>\POS(#2,#3)</DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>\xymatrix@1@=0pt@M=0pt@R=.5mm{#4}</DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>\endxy}</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>\determinantdiagram{</DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>*+<1mm>[F-:<10pt>]{k_1} \ar@/_.7pc/[ddddrrrrr] & l_1 & 0 & \cdots & 0 & *+<1mm>[F-:<10pt>]{b_1} \\</DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>0 & k_2 & l_2 & \ddots & \vdots & b_2 \\</DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>\vdots & \ddots & \ddots & \ddots & 0 & \vdots \\</DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>0 & \cdots & 0 & k_{N-1} & l_{N-1} & b_{N-1} \\</DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>*+<1mm>[F-:<10pt>]{l_N} \ar@/^1pc/[uuuurrrrr] & -l_N l_1 & \cdots & -l_N l_1 \cdots l_{N-2} & k_N & *+<1mm>[F-:<10pt>]{b_N}</DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>}{70}{-14}{</DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>*+<1mm>[F-:<10pt>]{k_1 b_N}\ar@{<-}@/_7mm/["*"rrrrr] & *+<1mm>[F-:<10pt>]{- l_N b_1}\ar@{<-}@/^5mm/["*"ddddrrrr]</DIV><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>}</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Thanks very much,</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Roger</DIV><BR><DIV> <SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><DIV>********************************</DIV><DIV><BR></DIV><DIV>Roger Hart</DIV><DIV>Assistant Professor, Departments of History and Asian Studies</DIV><DIV>University of Texas at Austin</DIV><DIV><BR></DIV><DIV>office: Room 470, Burdine Hall</DIV><DIV>office phone: 512-475-7258</DIV><DIV>department fax: 512-475-7222</DIV><DIV>email: <A href="mailto:rhart@mail.utexas.edu">rhart@mail.utexas.edu</A></DIV><DIV><A href="http://uts.cc.utexas.edu/~rhart">http://uts.cc.utexas.edu/~rhart</A></DIV><DIV><BR></DIV><DIV>*********************************</DIV><BR class="Apple-interchange-newline"></SPAN> </DIV><BR></BODY></HTML>