diff --git a/man/test_functions.Rd b/man/test_functions.Rd
index a40247d9a9ace522d40631c27e756596f1b7d68b..68eb02d0771cb4c6703a4b87477574f80f2f3858 100755
--- a/man/test_functions.Rd
+++ b/man/test_functions.Rd
@@ -95,7 +95,7 @@ The \bold{Shifted Schwefel's Problem 1.2} function is unimodal, non-separable, a
 \deqn{ sschwefel1\_2 = \sum_{i=1}^{n} {  \left(\sum_{j=1}^{i} {x_{j}} \right)^2 } + f\_bias \ ; \ -500 \leq x_i \leq 500 \ ; \ i=1,2,\ldots,n  } \cr
 
 
-Some optimisation algorithms take advantage of the known property of the benchmark functions, such as local optima lying along the coordinate axes, global optimum having the same values or many variables and so on. In order to avoid the previous shortcomings, shifting vector and a single bias is introduced for some benchmark functions, reported afterwards.
+Some optimisation algorithms take advantage of known properties of the benchmark functions, such as local optima lying along the coordinate axes, global optimum having the same values for many variables and so on. In order to avoid the previous shortcomings, shifting vector and a single bias is introduced for some benchmark functions, reported afterwards.
 
 The \bold{Shifted Ackley} is defined by:
 \deqn{ sackley = 20+\exp(1)-20\exp\left(-0.2\sqrt{\frac{1}{n}\sum_{i=1}^{n}z_{i}^2}\right)-\exp\left(\frac{1}{n}\sum_{i=1}^{n}\cos(2\pi z_{i})\right) + f\_bias , z=x-o ; \ i=1,2,\ldots,n } \cr