diff --git a/R/assert.R b/R/assert.R
index a7a47b6..132f173 100644
--- a/R/assert.R
+++ b/R/assert.R
@@ -35,12 +35,7 @@ validate <- function(expr) {
 #' @return Invisibly returns `NULL`.
 #' @family validation methods
 #' @author N. Frerebeau
-#' @name check-package
-#' @rdname check-package
-NULL
-
 #' @export
-#' @rdname check-package
 assert_package <- function(x, ask = TRUE) {
   ok <- vapply(X = x, FUN = requireNamespace, FUN.VALUE = logical(1),
                quietly = TRUE)
@@ -73,7 +68,7 @@ assert_package <- function(x, ask = TRUE) {
 }
 
 #' @export
-#' @rdname check-package
+#' @rdname assert_package
 needs <- assert_package
 
 # Types ========================================================================
@@ -87,12 +82,7 @@ needs <- assert_package
 #'  Throws an error, if any, and returns `x` invisibly otherwise.
 #' @author N. Frerebeau
 #' @family validation methods
-#' @name check-type
-#' @rdname check-type
-NULL
-
 #' @export
-#' @rdname check-type
 assert_type <- function(x, expected) {
   arg <- deparse(substitute(x))
   predicate <- switch(
@@ -115,7 +105,7 @@ assert_type <- function(x, expected) {
 }
 
 #' @export
-#' @rdname check-type
+#' @rdname assert_type
 assert_scalar <- function(x, expected) {
   arg <- deparse(substitute(x))
   predicate <- switch(
@@ -138,7 +128,7 @@ assert_scalar <- function(x, expected) {
 }
 
 #' @export
-#' @rdname check-type
+#' @rdname assert_type
 assert_function <- function(x) {
   arg <- deparse(substitute(x))
   if (!is.function(x)) {
@@ -149,7 +139,7 @@ assert_function <- function(x) {
 }
 
 # Attributes ===================================================================
-#' Check Object Attributes
+#' Check Object Length/Dimensions
 #'
 #' @param x An object to be checked.
 #' @param expected An appropriate expected value.
@@ -158,34 +148,7 @@ assert_function <- function(x) {
 #'  Throws an error, if any, and returns `x` invisibly otherwise.
 #' @author N. Frerebeau
 #' @family validation methods
-#' @name check-attribute
-#' @rdname check-attribute
-NULL
-
 #' @export
-#' @rdname check-attribute
-assert_empty <- function(x) {
-  arg <- deparse(substitute(x))
-  if (!is_empty(x)) {
-    msg <- sprintf("%s must be empty.", sQuote(arg))
-    throw_error("error_bad_dimensions", msg)
-  }
-  invisible(x)
-}
-
-#' @export
-#' @rdname check-attribute
-assert_filled <- function(x) {
-  arg <- deparse(substitute(x))
-  if (is_empty(x)) {
-    msg <- sprintf("%s must not be empty.", sQuote(arg))
-    throw_error("error_bad_dimensions", msg)
-  }
-  invisible(x)
-}
-
-#' @export
-#' @rdname check-attribute
 assert_length <- function(x, expected, empty = FALSE) {
   arg <- deparse(substitute(x))
   if (!(empty & is_empty(x)) && !has_length(x, n = expected)) {
@@ -197,7 +160,7 @@ assert_length <- function(x, expected, empty = FALSE) {
 }
 
 #' @export
-#' @rdname check-attribute
+#' @rdname assert_length
 assert_lengths <- function(x, expected) {
   arg <- deparse(substitute(x))
   n <- lengths(x)
@@ -211,7 +174,29 @@ assert_lengths <- function(x, expected) {
 }
 
 #' @export
-#' @rdname check-attribute
+#' @rdname assert_length
+assert_empty <- function(x) {
+  arg <- deparse(substitute(x))
+  if (!is_empty(x)) {
+    msg <- sprintf("%s must be empty.", sQuote(arg))
+    throw_error("error_bad_dimensions", msg)
+  }
+  invisible(x)
+}
+
+#' @export
+#' @rdname assert_length
+assert_filled <- function(x) {
+  arg <- deparse(substitute(x))
+  if (is_empty(x)) {
+    msg <- sprintf("%s must not be empty.", sQuote(arg))
+    throw_error("error_bad_dimensions", msg)
+  }
+  invisible(x)
+}
+
+#' @export
+#' @rdname assert_length
 assert_dimensions <- function(x, expected) {
   arg <- deparse(substitute(x))
   n <- dim(x)
@@ -224,8 +209,15 @@ assert_dimensions <- function(x, expected) {
   invisible(x)
 }
 
+#' Check Object Names
+#'
+#' @param x An object to be checked.
+#' @param expected An appropriate expected value.
+#' @return
+#'  Throws an error, if any, and returns `x` invisibly otherwise.
+#' @author N. Frerebeau
+#' @family validation methods
 #' @export
-#' @rdname check-attribute
 assert_names <- function(x, expected) {
   arg <- deparse(substitute(x))
   if (!has_names(x, names = expected)) {
@@ -241,7 +233,7 @@ assert_names <- function(x, expected) {
 }
 
 #' @export
-#' @rdname check-attribute
+#' @rdname assert_names
 assert_dimnames <- function(x, expected) {
   arg <- deparse(substitute(x))
   if (!identical(dimnames(x), expected)) {
@@ -252,7 +244,7 @@ assert_dimnames <- function(x, expected) {
 }
 
 #' @export
-#' @rdname check-attribute
+#' @rdname assert_names
 assert_rownames <- function(x, expected) {
   arg <- deparse(substitute(x))
   if (!identical(rownames(x), expected)) {
@@ -263,7 +255,7 @@ assert_rownames <- function(x, expected) {
 }
 
 #' @export
-#' @rdname check-attribute
+#' @rdname assert_names
 assert_colnames <- function(x, expected) {
   arg <- deparse(substitute(x))
   if (!identical(colnames(x), expected)) {
@@ -284,12 +276,12 @@ assert_colnames <- function(x, expected) {
 #'  Throws an error, if any, and returns `x` invisibly otherwise.
 #' @author N. Frerebeau
 #' @family validation methods
-#' @name check-data
-#' @rdname check-data
+#' @name assert_data
+#' @rdname assert_data
 NULL
 
 #' @export
-#' @rdname check-data
+#' @rdname assert_data
 assert_missing <- function(x) {
   arg <- deparse(substitute(x))
   n <- sum(is.na(x))
@@ -302,7 +294,7 @@ assert_missing <- function(x) {
 }
 
 #' @export
-#' @rdname check-data
+#' @rdname assert_data
 assert_infinite <- function(x) {
   arg <- deparse(substitute(x))
   n <- sum(is.infinite(x))
@@ -315,7 +307,7 @@ assert_infinite <- function(x) {
 }
 
 #' @export
-#' @rdname check-data
+#' @rdname assert_data
 assert_unique <- function(x) {
   arg <- deparse(substitute(x))
   if (has_duplicates(x)) {
@@ -336,12 +328,12 @@ assert_unique <- function(x) {
 #'  Throws an error, if any, and returns `x` invisibly otherwise.
 #' @author N. Frerebeau
 #' @family validation methods
-#' @name check-numeric
-#' @rdname check-numeric
+#' @name assert_numeric
+#' @rdname assert_numeric
 NULL
 
 #' @export
-#' @rdname check-numeric
+#' @rdname assert_numeric
 assert_count <- function(x, na.rm = FALSE, ...) {
   arg <- deparse(substitute(x))
   if (!all(is_whole(x, ...), na.rm = na.rm)) {
@@ -352,11 +344,11 @@ assert_count <- function(x, na.rm = FALSE, ...) {
 }
 
 #' @export
-#' @rdname check-numeric
+#' @rdname assert_numeric
 assert_whole <- assert_count
 
 #' @export
-#' @rdname check-numeric
+#' @rdname assert_numeric
 assert_positive <- function(x, na.rm = FALSE, ...) {
   arg <- deparse(substitute(x))
   if (!all(is_positive(x, ...), na.rm = na.rm)) {
@@ -367,7 +359,7 @@ assert_positive <- function(x, na.rm = FALSE, ...) {
 }
 
 #' @export
-#' @rdname check-numeric
+#' @rdname assert_numeric
 assert_negative <- function(x, na.rm = FALSE, ...) {
   arg <- deparse(substitute(x))
   if (!all(is_negative(x, ...), na.rm = na.rm)) {
@@ -378,7 +370,7 @@ assert_negative <- function(x, na.rm = FALSE, ...) {
 }
 
 #' @export
-#' @rdname check-numeric
+#' @rdname assert_numeric
 assert_odd <- function(x, na.rm = FALSE, ...) {
   arg <- deparse(substitute(x))
   if (!all(is_odd(x, ...), na.rm = na.rm)) {
@@ -389,7 +381,7 @@ assert_odd <- function(x, na.rm = FALSE, ...) {
 }
 
 #' @export
-#' @rdname check-numeric
+#' @rdname assert_numeric
 assert_even <- function(x, na.rm = FALSE, ...) {
   arg <- deparse(substitute(x))
   if (!all(is_even(x, ...), na.rm = na.rm)) {
@@ -407,12 +399,7 @@ assert_even <- function(x, na.rm = FALSE, ...) {
 #'  Throws an error, if any, and returns `x` invisibly otherwise.
 #' @author N. Frerebeau
 #' @family validation methods
-#' @name check-numeric-trend
-#' @rdname check-numeric-trend
-NULL
-
 #' @export
-#' @rdname check-numeric-trend
 assert_constant <- function(x, ...) {
   arg <- deparse(substitute(x))
   if (!is_constant(x, ...)) {
@@ -423,7 +410,7 @@ assert_constant <- function(x, ...) {
 }
 
 #' @export
-#' @rdname check-numeric-trend
+#' @rdname assert_constant
 assert_decreasing <- function(x, ...) {
   arg <- deparse(substitute(x))
   if (!is_decreasing(x, ...)) {
@@ -434,7 +421,7 @@ assert_decreasing <- function(x, ...) {
 }
 
 #' @export
-#' @rdname check-numeric-trend
+#' @rdname assert_constant
 assert_increasing <- function(x, ...) {
   arg <- deparse(substitute(x))
   if (!is_increasing(x, ...)) {
@@ -452,12 +439,7 @@ assert_increasing <- function(x, ...) {
 #'  Throws an error, if any, and returns `x` invisibly otherwise.
 #' @author N. Frerebeau
 #' @family validation methods
-#' @name check-numeric-comparison
-#' @rdname check-numeric-comparison
-NULL
-
 #' @export
-#' @rdname check-numeric-comparison
 assert_lower <- function(x, y, ...) {
   arg_x <- deparse(substitute(x))
   arg_y <- deparse(substitute(y))
@@ -469,7 +451,7 @@ assert_lower <- function(x, y, ...) {
 }
 
 #' @export
-#' @rdname check-numeric-comparison
+#' @rdname assert_lower
 assert_greater <- function(x, y, ...) {
   arg_x <- deparse(substitute(x))
   arg_y <- deparse(substitute(y))
@@ -487,28 +469,23 @@ assert_greater <- function(x, y, ...) {
 #' @return Throw an error, if any, and returns `x` invisibly otherwise.
 #' @author N. Frerebeau
 #' @family validation methods
-#' @name check-matrix
-#' @rdname check-matrix
-NULL
-
 #' @export
-#' @rdname check-matrix
-assert_symmetric <- function(x) {
+assert_square <- function(x) {
   arg <- deparse(substitute(x))
-  if (!is_symmetric(x)) {
-    msg <- sprintf("%s must be a symmetric matrix.", sQuote(arg))
+  if (!is_square(x)) {
+    k <- paste0(dim(x), collapse = " x ")
+    msg <- sprintf("%s must be a square matrix, not %s.", sQuote(arg), k)
     throw_error("error_bad_matrix", msg)
   }
   invisible(x)
 }
 
 #' @export
-#' @rdname check-matrix
-assert_square <- function(x) {
+#' @rdname assert_square
+assert_symmetric <- function(x) {
   arg <- deparse(substitute(x))
-  if (!is_square(x)) {
-    k <- paste0(dim(x), collapse = " x ")
-    msg <- sprintf("%s must be a sqaure matrix, not %s.", sQuote(arg), k)
+  if (!is_symmetric(x)) {
+    msg <- sprintf("%s must be a symmetric matrix.", sQuote(arg))
     throw_error("error_bad_matrix", msg)
   }
   invisible(x)
@@ -522,13 +499,8 @@ assert_square <- function(x) {
 # @return Throw an error, if any.
 # @author N. Frerebeau
 # @family validation methods
-# @name check-graph
-# @rdname check-graph
 # @keywords internal
-NULL
-
 # @export
-# @rdname check-graph
 # assert_dag <- function(x) {
 #   arg <- deparse(substitute(x))
 #   if (!is_dag(x)) {
diff --git a/R/predicates.R b/R/predicates.R
index 83ceca3..7b869c5 100644
--- a/R/predicates.R
+++ b/R/predicates.R
@@ -40,6 +40,13 @@ NULL
 has_length <- function(x, n = NULL) {
   if (is.null(n)) length(x) > 0 else length(x) == n
 }
+#' @export
+#' @rdname predicate-utils
+is_empty <- function(x) {
+  if (!is.null(dim(x))) nrow(x) == 0 || ncol(x) == 0
+  else length(x) == 0
+}
+
 #' @export
 #' @rdname predicate-utils
 has_names <- function(x, names = NULL) {
@@ -49,11 +56,7 @@ has_names <- function(x, names = NULL) {
     identical(names(x), names)
   }
 }
-#' @export
-#' @rdname predicate-utils
-has_duplicates <- function(x) {
-  any(duplicated(x))
-}
+
 #' @export
 #' @rdname predicate-utils
 has_missing <- function(x) {
@@ -64,17 +67,18 @@ has_missing <- function(x) {
 has_infinite <- function(x) {
   any(is.infinite(x))
 }
-#' @export
-#' @rdname predicate-utils
-is_empty <- function(x) {
-  any((dim(x) %||% length(x)) == 0)
-}
+
 #' @export
 #' @rdname predicate-utils
 is_unique <- function(x, na.rm = FALSE) {
   if (na.rm) x <- stats::na.omit(x)
   length(unique(x)) == 1
 }
+#' @export
+#' @rdname predicate-utils
+has_duplicates <- function(x) {
+  any(duplicated(x))
+}
 
 # Type =========================================================================
 #' Type Predicates
@@ -149,47 +153,47 @@ is_message <- function(x) {
 #' @param x An object to be tested.
 #' @return A [`logical`] scalar.
 #' @family predicates
-#' @name predicate-scalar
-#' @rdname predicate-scalar
+#' @name is_scalar
+#' @rdname is_scalar
 NULL
 
 #' @export
-#' @rdname predicate-scalar
+#' @rdname is_scalar
 is_scalar_list <- function(x) {
   is_list(x) && length(x) == 1
 }
 #' @export
-#' @rdname predicate-scalar
+#' @rdname is_scalar
 is_scalar_atomic <- function(x) {
   is_atomic(x) && length(x) == 1
 }
 #' @export
-#' @rdname predicate-scalar
+#' @rdname is_scalar
 is_scalar_vector <- function(x) {
   is_vector(x) && length(x) == 1
 }
 #' @export
-#' @rdname predicate-scalar
+#' @rdname is_scalar
 is_scalar_numeric <- function(x) {
   is_numeric(x) && length(x) == 1
 }
 #' @export
-#' @rdname predicate-scalar
+#' @rdname is_scalar
 is_scalar_integer <- function(x) {
   is_integer(x) && length(x) == 1
 }
 #' @export
-#' @rdname predicate-scalar
+#' @rdname is_scalar
 is_scalar_double <- function(x) {
   is_double(x) && length(x) == 1
 }
 #' @export
-#' @rdname predicate-scalar
+#' @rdname is_scalar
 is_scalar_character <- function(x) {
   is_character(x) && length(x) == 1
 }
 #' @export
-#' @rdname predicate-scalar
+#' @rdname is_scalar
 is_scalar_logical <- function(x) {
   is_logical(x) && length(x) == 1
 }
@@ -338,13 +342,8 @@ is_symmetric <- function(x) {
 #  Kahn, A. B. (1962). Topological sorting of large networks. *Communications
 #  of the ACM*, 5(11), p. 558-562. \doi{10.1145/368996.369025}.
 # @family predicates
-# @name predicate-graph
-# @rdname predicate-graph
 # @keywords internal
-NULL
-
 # @export
-# @rdname predicate-graph
 # is_dag <- function(x) {
 #   # Get edges
 #   G <- matrix2edges(x)
diff --git a/man/check-numeric-trend.Rd b/man/assert_constant.Rd
similarity index 70%
rename from man/check-numeric-trend.Rd
rename to man/assert_constant.Rd
index a94ff9f..9b2a862 100644
--- a/man/check-numeric-trend.Rd
+++ b/man/assert_constant.Rd
@@ -1,7 +1,6 @@
 % Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/assert.R
-\name{check-numeric-trend}
-\alias{check-numeric-trend}
+\name{assert_constant}
 \alias{assert_constant}
 \alias{assert_decreasing}
 \alias{assert_increasing}
@@ -26,13 +25,14 @@ Check Numeric Trend
 }
 \seealso{
 Other validation methods: 
-\code{\link{check-attribute}},
-\code{\link{check-data}},
-\code{\link{check-matrix}},
-\code{\link{check-numeric-comparison}},
-\code{\link{check-numeric}},
-\code{\link{check-package}},
-\code{\link{check-type}},
+\code{\link{assert_data}},
+\code{\link{assert_length}()},
+\code{\link{assert_lower}()},
+\code{\link{assert_names}()},
+\code{\link{assert_numeric}},
+\code{\link{assert_package}()},
+\code{\link{assert_square}()},
+\code{\link{assert_type}()},
 \code{\link{validate}()}
 }
 \author{
diff --git a/man/check-data.Rd b/man/assert_data.Rd
similarity index 72%
rename from man/check-data.Rd
rename to man/assert_data.Rd
index 2cf57cc..90213e6 100644
--- a/man/check-data.Rd
+++ b/man/assert_data.Rd
@@ -1,7 +1,7 @@
 % Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/assert.R
-\name{check-data}
-\alias{check-data}
+\name{assert_data}
+\alias{assert_data}
 \alias{assert_missing}
 \alias{assert_infinite}
 \alias{assert_unique}
@@ -28,13 +28,14 @@ missing (\code{NA}, \code{NaN}) or infinite (\code{Inf}) value.
 }
 \seealso{
 Other validation methods: 
-\code{\link{check-attribute}},
-\code{\link{check-matrix}},
-\code{\link{check-numeric-comparison}},
-\code{\link{check-numeric-trend}},
-\code{\link{check-numeric}},
-\code{\link{check-package}},
-\code{\link{check-type}},
+\code{\link{assert_constant}()},
+\code{\link{assert_length}()},
+\code{\link{assert_lower}()},
+\code{\link{assert_names}()},
+\code{\link{assert_numeric}},
+\code{\link{assert_package}()},
+\code{\link{assert_square}()},
+\code{\link{assert_type}()},
 \code{\link{validate}()}
 }
 \author{
diff --git a/man/check-attribute.Rd b/man/assert_length.Rd
similarity index 58%
rename from man/check-attribute.Rd
rename to man/assert_length.Rd
index d6e5390..4b26b0d 100644
--- a/man/check-attribute.Rd
+++ b/man/assert_length.Rd
@@ -1,35 +1,22 @@
 % Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/assert.R
-\name{check-attribute}
-\alias{check-attribute}
-\alias{assert_empty}
-\alias{assert_filled}
+\name{assert_length}
 \alias{assert_length}
 \alias{assert_lengths}
+\alias{assert_empty}
+\alias{assert_filled}
 \alias{assert_dimensions}
-\alias{assert_names}
-\alias{assert_dimnames}
-\alias{assert_rownames}
-\alias{assert_colnames}
-\title{Check Object Attributes}
+\title{Check Object Length/Dimensions}
 \usage{
-assert_empty(x)
-
-assert_filled(x)
-
 assert_length(x, expected, empty = FALSE)
 
 assert_lengths(x, expected)
 
-assert_dimensions(x, expected)
-
-assert_names(x, expected)
-
-assert_dimnames(x, expected)
+assert_empty(x)
 
-assert_rownames(x, expected)
+assert_filled(x)
 
-assert_colnames(x, expected)
+assert_dimensions(x, expected)
 }
 \arguments{
 \item{x}{An object to be checked.}
@@ -42,17 +29,18 @@ assert_colnames(x, expected)
 Throws an error, if any, and returns \code{x} invisibly otherwise.
 }
 \description{
-Check Object Attributes
+Check Object Length/Dimensions
 }
 \seealso{
 Other validation methods: 
-\code{\link{check-data}},
-\code{\link{check-matrix}},
-\code{\link{check-numeric-comparison}},
-\code{\link{check-numeric-trend}},
-\code{\link{check-numeric}},
-\code{\link{check-package}},
-\code{\link{check-type}},
+\code{\link{assert_constant}()},
+\code{\link{assert_data}},
+\code{\link{assert_lower}()},
+\code{\link{assert_names}()},
+\code{\link{assert_numeric}},
+\code{\link{assert_package}()},
+\code{\link{assert_square}()},
+\code{\link{assert_type}()},
 \code{\link{validate}()}
 }
 \author{
diff --git a/man/check-numeric-comparison.Rd b/man/assert_lower.Rd
similarity index 68%
rename from man/check-numeric-comparison.Rd
rename to man/assert_lower.Rd
index 6bfbd60..bddbf43 100644
--- a/man/check-numeric-comparison.Rd
+++ b/man/assert_lower.Rd
@@ -1,7 +1,6 @@
 % Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/assert.R
-\name{check-numeric-comparison}
-\alias{check-numeric-comparison}
+\name{assert_lower}
 \alias{assert_lower}
 \alias{assert_greater}
 \title{Check Numeric Relations}
@@ -23,13 +22,14 @@ Check Numeric Relations
 }
 \seealso{
 Other validation methods: 
-\code{\link{check-attribute}},
-\code{\link{check-data}},
-\code{\link{check-matrix}},
-\code{\link{check-numeric-trend}},
-\code{\link{check-numeric}},
-\code{\link{check-package}},
-\code{\link{check-type}},
+\code{\link{assert_constant}()},
+\code{\link{assert_data}},
+\code{\link{assert_length}()},
+\code{\link{assert_names}()},
+\code{\link{assert_numeric}},
+\code{\link{assert_package}()},
+\code{\link{assert_square}()},
+\code{\link{assert_type}()},
 \code{\link{validate}()}
 }
 \author{
diff --git a/man/assert_names.Rd b/man/assert_names.Rd
new file mode 100644
index 0000000..9ce3c00
--- /dev/null
+++ b/man/assert_names.Rd
@@ -0,0 +1,44 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/assert.R
+\name{assert_names}
+\alias{assert_names}
+\alias{assert_dimnames}
+\alias{assert_rownames}
+\alias{assert_colnames}
+\title{Check Object Names}
+\usage{
+assert_names(x, expected)
+
+assert_dimnames(x, expected)
+
+assert_rownames(x, expected)
+
+assert_colnames(x, expected)
+}
+\arguments{
+\item{x}{An object to be checked.}
+
+\item{expected}{An appropriate expected value.}
+}
+\value{
+Throws an error, if any, and returns \code{x} invisibly otherwise.
+}
+\description{
+Check Object Names
+}
+\seealso{
+Other validation methods: 
+\code{\link{assert_constant}()},
+\code{\link{assert_data}},
+\code{\link{assert_length}()},
+\code{\link{assert_lower}()},
+\code{\link{assert_numeric}},
+\code{\link{assert_package}()},
+\code{\link{assert_square}()},
+\code{\link{assert_type}()},
+\code{\link{validate}()}
+}
+\author{
+N. Frerebeau
+}
+\concept{validation methods}
diff --git a/man/check-numeric.Rd b/man/assert_numeric.Rd
similarity index 76%
rename from man/check-numeric.Rd
rename to man/assert_numeric.Rd
index e968085..37a4528 100644
--- a/man/check-numeric.Rd
+++ b/man/assert_numeric.Rd
@@ -1,7 +1,7 @@
 % Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/assert.R
-\name{check-numeric}
-\alias{check-numeric}
+\name{assert_numeric}
+\alias{assert_numeric}
 \alias{assert_count}
 \alias{assert_whole}
 \alias{assert_positive}
@@ -38,13 +38,14 @@ Check Numeric Values
 }
 \seealso{
 Other validation methods: 
-\code{\link{check-attribute}},
-\code{\link{check-data}},
-\code{\link{check-matrix}},
-\code{\link{check-numeric-comparison}},
-\code{\link{check-numeric-trend}},
-\code{\link{check-package}},
-\code{\link{check-type}},
+\code{\link{assert_constant}()},
+\code{\link{assert_data}},
+\code{\link{assert_length}()},
+\code{\link{assert_lower}()},
+\code{\link{assert_names}()},
+\code{\link{assert_package}()},
+\code{\link{assert_square}()},
+\code{\link{assert_type}()},
 \code{\link{validate}()}
 }
 \author{
diff --git a/man/check-package.Rd b/man/assert_package.Rd
similarity index 79%
rename from man/check-package.Rd
rename to man/assert_package.Rd
index 69d8bef..0b20d48 100644
--- a/man/check-package.Rd
+++ b/man/assert_package.Rd
@@ -1,7 +1,6 @@
 % Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/assert.R
-\name{check-package}
-\alias{check-package}
+\name{assert_package}
 \alias{assert_package}
 \alias{needs}
 \title{Check the Availability of a Package}
@@ -33,13 +32,14 @@ the user will be asked to install the packages.
 }
 \seealso{
 Other validation methods: 
-\code{\link{check-attribute}},
-\code{\link{check-data}},
-\code{\link{check-matrix}},
-\code{\link{check-numeric-comparison}},
-\code{\link{check-numeric-trend}},
-\code{\link{check-numeric}},
-\code{\link{check-type}},
+\code{\link{assert_constant}()},
+\code{\link{assert_data}},
+\code{\link{assert_length}()},
+\code{\link{assert_lower}()},
+\code{\link{assert_names}()},
+\code{\link{assert_numeric}},
+\code{\link{assert_square}()},
+\code{\link{assert_type}()},
 \code{\link{validate}()}
 }
 \author{
diff --git a/man/check-matrix.Rd b/man/assert_square.Rd
similarity index 64%
rename from man/check-matrix.Rd
rename to man/assert_square.Rd
index 825fb91..ace3be2 100644
--- a/man/check-matrix.Rd
+++ b/man/assert_square.Rd
@@ -1,14 +1,13 @@
 % Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/assert.R
-\name{check-matrix}
-\alias{check-matrix}
-\alias{assert_symmetric}
+\name{assert_square}
 \alias{assert_square}
+\alias{assert_symmetric}
 \title{Check Matrix}
 \usage{
-assert_symmetric(x)
-
 assert_square(x)
+
+assert_symmetric(x)
 }
 \arguments{
 \item{x}{A \code{\link{matrix}} to be checked.}
@@ -21,13 +20,14 @@ Check Matrix
 }
 \seealso{
 Other validation methods: 
-\code{\link{check-attribute}},
-\code{\link{check-data}},
-\code{\link{check-numeric-comparison}},
-\code{\link{check-numeric-trend}},
-\code{\link{check-numeric}},
-\code{\link{check-package}},
-\code{\link{check-type}},
+\code{\link{assert_constant}()},
+\code{\link{assert_data}},
+\code{\link{assert_length}()},
+\code{\link{assert_lower}()},
+\code{\link{assert_names}()},
+\code{\link{assert_numeric}},
+\code{\link{assert_package}()},
+\code{\link{assert_type}()},
 \code{\link{validate}()}
 }
 \author{
diff --git a/man/check-type.Rd b/man/assert_type.Rd
similarity index 74%
rename from man/check-type.Rd
rename to man/assert_type.Rd
index 27ed4ea..9d8c9ae 100644
--- a/man/check-type.Rd
+++ b/man/assert_type.Rd
@@ -1,7 +1,6 @@
 % Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/assert.R
-\name{check-type}
-\alias{check-type}
+\name{assert_type}
 \alias{assert_type}
 \alias{assert_scalar}
 \alias{assert_function}
@@ -28,13 +27,14 @@ Check Data Types
 }
 \seealso{
 Other validation methods: 
-\code{\link{check-attribute}},
-\code{\link{check-data}},
-\code{\link{check-matrix}},
-\code{\link{check-numeric-comparison}},
-\code{\link{check-numeric-trend}},
-\code{\link{check-numeric}},
-\code{\link{check-package}},
+\code{\link{assert_constant}()},
+\code{\link{assert_data}},
+\code{\link{assert_length}()},
+\code{\link{assert_lower}()},
+\code{\link{assert_names}()},
+\code{\link{assert_numeric}},
+\code{\link{assert_package}()},
+\code{\link{assert_square}()},
 \code{\link{validate}()}
 }
 \author{
diff --git a/man/predicate-scalar.Rd b/man/is_scalar.Rd
similarity index 94%
rename from man/predicate-scalar.Rd
rename to man/is_scalar.Rd
index 013902f..6343966 100644
--- a/man/predicate-scalar.Rd
+++ b/man/is_scalar.Rd
@@ -1,7 +1,7 @@
 % Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/predicates.R
-\name{predicate-scalar}
-\alias{predicate-scalar}
+\name{is_scalar}
+\alias{is_scalar}
 \alias{is_scalar_list}
 \alias{is_scalar_atomic}
 \alias{is_scalar_vector}
diff --git a/man/predicate-matrix.Rd b/man/predicate-matrix.Rd
index b46f3c1..0119787 100644
--- a/man/predicate-matrix.Rd
+++ b/man/predicate-matrix.Rd
@@ -24,8 +24,8 @@ A \code{\link{logical}} scalar.
 }
 \seealso{
 Other predicates: 
+\code{\link{is_scalar}},
 \code{\link{predicate-numeric}},
-\code{\link{predicate-scalar}},
 \code{\link{predicate-trend}},
 \code{\link{predicate-type}},
 \code{\link{predicate-utils}}
diff --git a/man/predicate-numeric.Rd b/man/predicate-numeric.Rd
index e58bd7d..4ac8790 100644
--- a/man/predicate-numeric.Rd
+++ b/man/predicate-numeric.Rd
@@ -46,8 +46,8 @@ Check numeric objects:
 }
 \seealso{
 Other predicates: 
+\code{\link{is_scalar}},
 \code{\link{predicate-matrix}},
-\code{\link{predicate-scalar}},
 \code{\link{predicate-trend}},
 \code{\link{predicate-type}},
 \code{\link{predicate-utils}}
diff --git a/man/predicate-trend.Rd b/man/predicate-trend.Rd
index 18752c2..24c8fad 100644
--- a/man/predicate-trend.Rd
+++ b/man/predicate-trend.Rd
@@ -42,9 +42,9 @@ is monotonically increasing or decreasing, respectively.
 }
 \seealso{
 Other predicates: 
+\code{\link{is_scalar}},
 \code{\link{predicate-matrix}},
 \code{\link{predicate-numeric}},
-\code{\link{predicate-scalar}},
 \code{\link{predicate-type}},
 \code{\link{predicate-utils}}
 }
diff --git a/man/predicate-type.Rd b/man/predicate-type.Rd
index 16c498e..4b7bedd 100644
--- a/man/predicate-type.Rd
+++ b/man/predicate-type.Rd
@@ -48,9 +48,9 @@ Type Predicates
 }
 \seealso{
 Other predicates: 
+\code{\link{is_scalar}},
 \code{\link{predicate-matrix}},
 \code{\link{predicate-numeric}},
-\code{\link{predicate-scalar}},
 \code{\link{predicate-trend}},
 \code{\link{predicate-utils}}
 }
diff --git a/man/predicate-utils.Rd b/man/predicate-utils.Rd
index e1137ea..bdb553a 100644
--- a/man/predicate-utils.Rd
+++ b/man/predicate-utils.Rd
@@ -3,27 +3,27 @@
 \name{predicate-utils}
 \alias{predicate-utils}
 \alias{has_length}
+\alias{is_empty}
 \alias{has_names}
-\alias{has_duplicates}
 \alias{has_missing}
 \alias{has_infinite}
-\alias{is_empty}
 \alias{is_unique}
+\alias{has_duplicates}
 \title{Utility Predicates}
 \usage{
 has_length(x, n = NULL)
 
-has_names(x, names = NULL)
+is_empty(x)
 
-has_duplicates(x)
+has_names(x, names = NULL)
 
 has_missing(x)
 
 has_infinite(x)
 
-is_empty(x)
-
 is_unique(x, na.rm = FALSE)
+
+has_duplicates(x)
 }
 \arguments{
 \item{x}{A \code{\link{vector}} to be tested.}
@@ -53,9 +53,9 @@ or infinite values.
 }
 \seealso{
 Other predicates: 
+\code{\link{is_scalar}},
 \code{\link{predicate-matrix}},
 \code{\link{predicate-numeric}},
-\code{\link{predicate-scalar}},
 \code{\link{predicate-trend}},
 \code{\link{predicate-type}}
 }
diff --git a/man/validate.Rd b/man/validate.Rd
index 7853b0a..350848a 100644
--- a/man/validate.Rd
+++ b/man/validate.Rd
@@ -17,14 +17,15 @@ Validate a Condition
 }
 \seealso{
 Other validation methods: 
-\code{\link{check-attribute}},
-\code{\link{check-data}},
-\code{\link{check-matrix}},
-\code{\link{check-numeric-comparison}},
-\code{\link{check-numeric-trend}},
-\code{\link{check-numeric}},
-\code{\link{check-package}},
-\code{\link{check-type}}
+\code{\link{assert_constant}()},
+\code{\link{assert_data}},
+\code{\link{assert_length}()},
+\code{\link{assert_lower}()},
+\code{\link{assert_names}()},
+\code{\link{assert_numeric}},
+\code{\link{assert_package}()},
+\code{\link{assert_square}()},
+\code{\link{assert_type}()}
 }
 \author{
 N. Frerebeau