Grade (bouldering)

In the sport of bouldering, problems are assigned technical grades according to several established systems, which are often distinct from those used in roped climbing. Bouldering grade systems in wide use include the Hueco "V" grades (known as the V-scale), Fontainebleau technical grades, route colors, Peak District grades, and British technical grades. Historically, the three-level "B" system and even the Yosemite Decimal System (sometimes with a "B" prepended, as in "B5.12") were also used.

The Gill "B" system

The B-System conceived by John Gill in the 1950s was a universal rating scheme for bouldering, having three categories: "B1" was defined as "... the highest level of difficulty in traditional roped climbing", "B2" was harder than B1, or "bouldering level", and the grade "B3" designated a route ascended only once, although tried by others on several occasions. When a B3 was ascended a second time, it was reclassified as a B2, or B1. Gill's idea was to attract climbers to the "new" sport of bouldering, but discourage turning that sport into a numbers race. His system depended heavily on traditional climbing standards, long before sport climbing came into existence. It was assumed that the scale would shift as traditional difficulty levels rose. Thus, e.g., a B1(1958) would be easier than a B1(1968).

Grading (education)

Grading in education is the process of applying standardized measurements of varying levels of achievement in a course. Another way the grade point average (GPA) can be determined is through extra curricular activities. Grades can be assigned as letters (generally A through F), as a range (for example 1 to 6), as a percentage of a total number of questions answered correctly, or as a number out of a possible total (for example out of 20 or 100).

In some countries, all grades from all current classes are averaged to create a Grade Point Average (GPA) for the marking period. The GPA is calculated by taking the number of grade points a student earned in a given period of time of middle school through high school. GPAs are also calculated for undergraduate and graduate students in most universities. The GPA can be used by potential employers or educational institutions to assess and compare applicants. A cumulative grade point average is a calculation of the average of all of a student's grades for all of his or her complete education career.

Paraphyly

In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and all descendants of that ancestor excluding a few—typically only one or two—monophyletic subgroups. The group is said to be paraphyletic with respect to the excluded subgroups. The term is commonly used in phylogenetics (a subfield of biology) and in linguistics.

The term was coined to apply to well-known taxa like reptiles (Reptilia) which, as commonly named and traditionally defined, is paraphyletic with respect to mammals and birds. Reptilia contains the last common ancestor of reptiles and all descendants of that ancestor—including all extant reptiles as well as the extinct mammal-like reptiles—except for mammals and birds. Other commonly recognized paraphyletic groups include fish and lizards.

If many subgroups are missing from the named group, it is said to be polyparaphyletic. A paraphyletic group cannot be a clade, which is a monophyletic group.

Phylogenetics

Relation to monophyletic groups