diff --git a/src/adapptlet.civet b/src/adapptlet.civet
index bfa902d..aacc327 100644
--- a/src/adapptlet.civet
+++ b/src/adapptlet.civet
@@ -266,16 +266,21 @@ function jToG(
       if scalar is scalar // not NaN
          (args.scalar ?= []).push scalar
          continue
-      unless jdep in cdata.elements
-         console.warn `Reference to unknown geometric entity ${jdep} in $jCom}`
-         return cmdr
-      usesCaptions.push jdep
-      {klass: depKlass, otherName: depGeo, ends} := cdata.elements[jdep]
-      (args[depKlass] ?= []).push depGeo
-      if depKlass is 'point'
-         (args.subpoints ?= []).push depGeo
-      else if depKlass is 'line'
-         (args.subpoints ?= []).push ...ends ?? []
+      if jdep is 'screen'
+         // special case for Joyce; assume xOyPlane
+         (args.plane ?= []).push 'xOyPlane'
+      else
+         unless jdep in cdata.elements
+            console.warn
+               `Reference to unknown geometric entity ${jdep} in ${jCom}`
+            return cmdr
+         usesCaptions.push jdep
+         {klass: depKlass, otherName: depGeo, ends} := cdata.elements[jdep]
+         (args[depKlass] ?= []).push depGeo
+         if depKlass is 'point'
+            (args.subpoints ?= []).push depGeo
+         else if depKlass is 'line'
+            (args.subpoints ?= []).push ...ends ?? []
    cmdr = classHandler[klass] name, method, args, index, cdata, colors, jname
    unless name is jname then cmdr.callbacks.push (api: AppletObject) =>
       api.setCaption name, jname
@@ -586,7 +591,7 @@ classHandler: Record<JoyceClass, ClassHandler> :=
       aux := name + 'aUx'
       pivotable := cdata.pivot and name !== pivotData[cdata.pivot].pivot
       parts[0].push name
-      // HACK: Special-case corrections for Joyce Elements Bk XI & XII
+      // HACK: Special-case corrections for Joyce Elements Bk XI -- XIII
       if cdata.title is 'XI.4'
          if name is 'Z' and method is 'fixed' and args.scalar?.length is 3
             method = 'perpendicular'
@@ -614,6 +619,23 @@ classHandler: Record<JoyceClass, ClassHandler> :=
          if (jname is 'a' and method is 'lineSlider'
              and args.subpoints?[1] is cdata.elements['1Y'].otherName)
             args.subpoints[1] = cdata.elements['1Z'].otherName
+      if cdata.title is 'XIII.17'
+         // Joyce's point perpendicular to a plane is ambiguous between
+         // two possible positions, and Geogebra's choice does not
+         // always agree with what Joyce's code did. So we just have to flip
+         // one of his choices in the dodecahedron
+         if name is 'U' and method is 'extend' and args.subpoints?[0] is "U'"
+            method = 'midpoint'
+            args.point = ["U'", "U'"] // hacky way to make U = U'
+      if cdata.title is 'Dodecahedron and cube'
+         // similar issues to XIII.17
+         if (name is 'VAB' or name is 'VBC') and method is 'perpendicular'
+            args.scalar = [1]
+      if cdata.title is 'XIII.18'
+         // Joyce just mistook where N is
+         if name is 'N' and method is 'intersection'
+            method = 'golden'
+            args.subpoints = ['B', 'F']
       switch method
          /angle(?:Bisector|Divider)/
             {center, foot} :=
@@ -679,6 +701,12 @@ classHandler: Record<JoyceClass, ClassHandler> :=
                : `Line(${pt[1]},${pt[2]})`
             commands.push
                `${name} = ClosestPoint(${destination}, ${pt[0]})`
+         'golden'
+            // Added in this implementation to ease fix of XIII.18
+            pt := args.subpoints
+            unless pt and pt.length is 2 then return
+            commands.push
+               `${name} = ${pt[0]} + ((sqrt(5)-1)/2)*(${pt[1]}-${pt[0]})`
          'intersection'
             // Checking Joyce source, means intersection of lines, not
             // intersection of line segments
@@ -736,15 +764,13 @@ classHandler: Record<JoyceClass, ClassHandler> :=
                   commands.push
                      `${name} = Rotate(${pt[1]}, pi/2, ${center}${inPlane})`
                when 3 // perpendicular **to** the plane
-                  // Uses lots of auxiliaries
                   radius := `Distance(${pt[1]}, ${pt[2]})`
+                  which := args.scalar ? args.scalar[0] : 2 //HACK: 2 vs 1??
                   commands.push
-                     `${aux}1 = Circle(${center}, ${radius}${inPlane})`
-                     `${aux}2 = PointIn(${aux}1)`
-                     `${aux}3 = PerpendicularLine(${center}${inPlane})`
-                     `${aux}4 = Plane(${aux}2, ${aux}3)`
-                     `${name} = Rotate(${aux}2, pi/2, ${center}, ${aux}4)`
-                  auxiliaries.push aux+n for n of [1..4]
+                     `${aux}1 = Sphere(${center}, ${radius})`
+                     `${aux}2 = PerpendicularLine(${center}${inPlane})`
+                     `${name} = Intersect(${aux}2,${aux}1,${which})`
+                  auxiliaries.push aux+1, aux+2
                when 4
                   commands.push
                      `${aux}1 = Ray(${center}, Rotate(${pt[1]}, pi/2, ${center}${inPlane}))`
@@ -932,7 +958,6 @@ classHandler: Record<JoyceClass, ClassHandler> :=
       aux := name + 'aUx'
       parts[1].push name
       circle .= ''
-      defaultPlane := cdata.is3d ? ', xOyPlane' : ''
       switch method
          'circumcircle'
             pt := args.subpoints
@@ -944,18 +969,17 @@ classHandler: Record<JoyceClass, ClassHandler> :=
             circle = `IntersectConic(${sph[0]}, ${sph[1]})`
          'radius'
             pt := args.subpoints
-            unless pt then return
-            inPlane := args.plane ? `, ${args.plane[0]}` : defaultPlane
-            switch pt.length
-               when 2
-                  [center, point] := pt
-                  ends[0] = center
-                  circle = `Circle(${center}, ${point}${inPlane})`
-               when 3
-                  center := pt[0]
-                  ends[0] = center
-                  radius := `Distance(${pt[1]}, ${pt[2]})`
-                  circle = `Circle(${center}, ${radius}${inPlane})`
+            unless pt and pt.length > 1 and pt.length < 4 then return
+            ends[0] = pt[0]
+            if pt.length is 2 and not cdata.is3d
+               circle = `Circle(${pt[0]}, ${pt[1]})`
+            else // 3d or three points
+               radIx := pt.length - 2
+               inPlane := (cdata.is3d
+                  ? args.plane ? `, ${args.plane[0]}` : ', xOyPlane'
+                  : '')
+               radius := `Distance(${pt[radIx]}, ${pt[radIx+1]})`
+               circle = `Circle(${pt[0]}, ${radius}${inPlane})`
       commands.push
          `${aux} = ${circle}`  // for the filling
          `${name} = ${circle}` // for the perimeter
@@ -978,9 +1002,14 @@ classHandler: Record<JoyceClass, ClassHandler> :=
                N = args.scalar[0]
             commands.push '' // hack, make sure there is a command
             parts[0].push pt[0], pt[1]
+            inPlane := cdata.is3d
+               ? args.plane ? `, ${args.plane[0]}` : ', xOyPlane'
+               : ''
             callbacks.push (api: AppletObject, moreParts: DimParts) =>
-               made:= api.evalCommandGetLabels
-                  `${name} = Polygon(${pt[0]},${pt[1]}, ${N})`
+               command := `${name} = Polygon(${pt[0]},${pt[1]}, ${N}${inPlane})`
+               made:= api.evalCommandGetLabels command
+               if adapParams.config?.commands
+                  console.log 'Finishing with', command, 'producing', made
                if not made return
                for each obj of made.split ','
                   if obj is name continue
@@ -1212,6 +1241,12 @@ classHandler: Record<JoyceClass, ClassHandler> :=
                      api.renameObject obj, newObj
                      moreParts[1].push newObj
                   base = ends[0]
+               else // need to grab the parts of the base, which become
+                    // parts of the polyhedron
+                  baseParts := cdata.elements[base].parts
+                  if baseParts
+                     parts[0].push ...baseParts[0]
+                     parts[1].push ...baseParts[1]
                made := api.evalCommandGetLabels
                   `${name} = Pyramid(${base}, ${ends[1]})`
                if not made return