* algebra/catdef.spad.pamphlet (DifferentialRing): Now extends

	DifferentialDomain.
	(DifferentialExtension): Check parameter for only DifferentialDomain.
	* algebra/dpolcat.spad.pamphlet (DifferentialPolynomialCategory):
	Likewise. 
	* algebra/lodop.spad.pamphlet (OppositeMonogenicLinearOperator):
	Likewise. 

5 files changed, 8 insertions, 17 deletions

diff --git a/src/algebra/Makefile.in b/src/algebra/Makefile.in
index 89983429..a70711d9 100644
--- a/src/algebra/Makefile.in
+++ b/src/algebra/Makefile.in
@@ -360,7 +360,7 @@ axiom_algebra_layer_0 = \
   RCAGG    RCAGG-   SETAGG   SETAGG-  HOAGG    HOAGG-   \
   TBAGG    TBAGG-   KDAGG    KDAGG-   DIAGG    DIAGG-   \
   DIOPS    DIOPS-   STRING   STRICAT  ISTRING  ILIST    \
-  LIST     DIFFDOM                                      \
+  LIST     DIFFDOM  DIFFDOM-                            \
   LINEXP   PATMAB   REAL     CHARZ    LOGIC    LOGIC-   \
   RTVALUE  SYSPTR
 
diff --git a/src/algebra/Makefile.pamphlet b/src/algebra/Makefile.pamphlet
index 9ed8ca3f..9f76645f 100644
--- a/src/algebra/Makefile.pamphlet
+++ b/src/algebra/Makefile.pamphlet
@@ -314,7 +314,7 @@ axiom_algebra_layer_0 = \
   RCAGG    RCAGG-   SETAGG   SETAGG-  HOAGG    HOAGG-   \
   TBAGG    TBAGG-   KDAGG    KDAGG-   DIAGG    DIAGG-   \
   DIOPS    DIOPS-   STRING   STRICAT  ISTRING  ILIST    \
-  LIST     DIFFDOM                                      \
+  LIST     DIFFDOM  DIFFDOM-                            \
   LINEXP   PATMAB   REAL     CHARZ    LOGIC    LOGIC-   \
   RTVALUE  SYSPTR
 
diff --git a/src/algebra/catdef.spad.pamphlet b/src/algebra/catdef.spad.pamphlet
index a7807009..1ea30684 100644
--- a/src/algebra/catdef.spad.pamphlet
+++ b/src/algebra/catdef.spad.pamphlet
@@ -403,21 +403,12 @@ DifferentialDomain(T: Type): Category == Type with
 ++   \spad{differentiate(x+y) = differentiate(x)+differentiate(y)}
 ++   \spad{differentiate(x*y) = x*differentiate(y) + differentiate(x)*y}
 
-DifferentialRing(): Category == Ring with
-    differentiate: % -> %
-         ++ differentiate(x) returns the derivative of x.
-         ++ This function is a simple differential operator
-         ++ where no variable needs to be specified.
-    D: % -> %
-         ++ D(x) returns the derivative of x.
-         ++ This function is a simple differential operator
-         ++ where no variable needs to be specified.
+DifferentialRing(): Category == Join(Ring,DifferentialDomain %) with
     differentiate: (%, NonNegativeInteger) -> %
          ++ differentiate(x, n) returns the n-th derivative of x.
     D: (%, NonNegativeInteger) -> %
          ++ D(x, n) returns the n-th derivative of x.
   add
-    D r == differentiate r
     differentiate(r, n) ==
       for i in 1..n repeat r := differentiate r
       r
@@ -455,7 +446,7 @@ DifferentialExtension(R:Ring): Category == Ring with
     D: (%, R -> R, NonNegativeInteger) -> %
        ++ D(x, deriv, n) differentiate x n times
        ++ using a derivation which extends deriv on R.
-    if R has DifferentialRing then DifferentialRing
+    if R has DifferentialDomain R then DifferentialRing
     if R has PartialDifferentialRing(Symbol) then
              PartialDifferentialRing(Symbol)
   add
@@ -466,7 +457,7 @@ DifferentialExtension(R:Ring): Category == Ring with
     D(x:%, derivation: R -> R, n:NonNegativeInteger) ==
             differentiate(x, derivation, n)
 
-    if R has DifferentialRing then
+    if R has DifferentialDomain R then
       differentiate x == differentiate(x, differentiate$R)
 
     if R has PartialDifferentialRing Symbol then
diff --git a/src/algebra/dpolcat.spad.pamphlet b/src/algebra/dpolcat.spad.pamphlet
index c5da0b47..65533281 100644
--- a/src/algebra/dpolcat.spad.pamphlet
+++ b/src/algebra/dpolcat.spad.pamphlet
@@ -300,7 +300,7 @@ DifferentialPolynomialCategory(R:Ring,S:OrderedSet,
       ++ separant(p) returns the
       ++ partial derivative of the differential polynomial p
       ++ with respect to its leader.
-    if R has DifferentialRing then
+    if R has DifferentialDomain R then
       InnerEvalable(S, R)
       InnerEvalable(S, $)
       Evalable $
@@ -394,7 +394,7 @@ DifferentialPolynomialCategory(R:Ring,S:OrderedSet,
     differentialVariables p ==
       removeDuplicates [variable v for v in variables p]
 
-    if R has DifferentialRing then
+    if R has DifferentialDomain R then
 
       makeVariable p == differentiate(p, #1)
 
diff --git a/src/algebra/lodop.spad.pamphlet b/src/algebra/lodop.spad.pamphlet
index 3ebad1d2..d4aba322 100644
--- a/src/algebra/lodop.spad.pamphlet
+++ b/src/algebra/lodop.spad.pamphlet
@@ -86,7 +86,7 @@ OppositeMonogenicLinearOperator(P, R): OPRcat == OPRdef where
    R: Ring
 
    OPRcat == MonogenicLinearOperator(R) with
-        if P has DifferentialRing then DifferentialRing
+        if P has DifferentialDomain P then DifferentialRing
         op: P -> $  ++ op(p) creates a value in $ equal to p in P.
         po: $ -> P  ++ po(q) creates a value in P equal to q in $.