関: half

WordNet

partially or to the extent of a half; "he was half hidden by the bushes"
one of two divisions into which some games or performances are divided: the two divisions are separated by an interval
(of siblings) related through one parent only; "a half brother"; "half sister"
consisting of one of two equivalent parts in value or quantity; "a half chicken"; "lasted a half hour"
partial; "gave me a half smile"; "he did only a half job"
divide by two; divide into halves; "Halve the cake"

PrepTutorEJDIC

halfの複数形
〈C〉〈U〉『半分』,2分の1;約半分 / 〈U〉《時刻を表す数詞と共に用いて》『半』,30分 / 〈C〉《おもに英》(2学期制の学校での)前(後)期 / 〈C〉(競技などの)前(後)半;(野球で1イニングの)表(裏) / 〈C〉=halfback / 『半分の』 / 不十分な,中途はんぱな / 『半ば』,半分[だけ] / 半時間だけ,30分だけ / 不完全に / かなり,ほとんど
…‘を'半分に分ける / (人と)…‘を'半分ずつ分け合う《+『名』+『with』+『名』〈人〉》 / …‘を'半減する

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/10/05 20:36:29」(JST)

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[Wiki en表示]

One half
prefixes	hemi- (from Greek) semi-/demi- (from Latin)
Binary	0.1 or 0.011111111111...
Decimal	0.5 or 0.499999999999...
Dozenal	0.6 or 0.5BBBBBBBBBBBB...
Hexadecimal	0.8 or 0.7FFFFFFFFFFF...
Continued fraction	[0; 1, 1] or [0; 2]
Single-precision floating point	3F000000 (hex) = 00111111000000000000000000000000 (binary)

One half is the irreducible fraction resulting from dividing one by two (½), or any number by its double; multiplication by one half is equivalent to division by two. Conversely, division by one half is equivalent to multiplication by two, or "doubling". One half appears often in mathematical equations, recipes, measurements, etc. Half can also be said to be one part of something divided into two equal parts.

For instance, the area S of a triangle is computed

S = ½ × base × perpendicular height.

One half also figures in the formula for calculating figurate numbers, such as triangular numbers and pentagonal numbers:

½ × n [(s - 2) n - (4 - s)]

and in the formula for computing magic constants for magic squares

M₂(n) = ½ × [n (n² + 1 )].

The Riemann hypothesis states that every nontrivial complex root of the Riemann zeta function has a real part equal to ½.

One half has two different decimal expansions, the familiar 0.5 and the recurring 0.49999999... It has a similar pair of expansions in any even base. It is a common trap to believe these expressions represent distinct numbers: see the proof that 0.999... equals 1 for detailed discussion of a related case.

Particularities in writing and language

Postal stamp, Ireland, 1940: one halfpenny postage due.

½ is also one of the few fractions to get a key of its own on typewriters (see fractions). It also gets its own point in some early extensions of ASCII at 171; and in Unicode, it gets its own code point at U+00BD (decimal 189) in the C1 Controls and Latin-1 Supplement block, and a cross-reference in the Number Forms block, which contains some other fractions.

One half is as well one of the few fractions which is commonly expressed in natural languages by suppletion rather than regular derivation; compare English one half with regular formations like one sixth from six.

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English Journal

Hemisphere-dependent holistic processing of familiar faces.

Ramon M, Rossion B.SourceInstitute of Psychology (IPSY) & Institute of Neuroscience (IoNS), Université catholique de Louvain, Belgium. meike.ramon@uclouvain.be
Brain and cognition.Brain Cogn.2012 Feb;78(1):7-13. doi: 10.1016/j.bandc.2011.10.009. Epub 2011 Nov 17.
In two behavioral experiments involving lateralized stimulus presentation, we tested whether one of the most commonly used measures of holistic face processing-the composite face effect-would be more pronounced for stimuli presented to the right as compared to the left hemisphere. In experiment 1, w
PMID 22099150

The Strength and Difficulties Questionnaire: Russian validation of the teacher version and comparison of teacher and student reports.

Ruchkin V, Koposov R, Vermeiren R, Schwab-Stone M.SourceDepartment of Social and Forensic Psychiatry, Division of Neuroscience, Karolinska Institute, Stockholm, Sweden; Forensic Psychiatric Clinic Sater, Sater, Sweden; Yale Child Study Center, 230 South Frontage Road, New Haven, CT 06520-7900, USA.
Journal of adolescence.J Adolesc.2012 Feb;35(1):87-96. Epub 2011 Jul 6.
OBJECTIVE: To confirm factor structure of the teacher Strengths and Difficulties Questionnaire (SDQ) and to compare teacher and student reports in Russian youth.METHOD: The SDQ and psychopathology measures were completed by teachers in a representative sample of urban adolescents (N = 528). The fa
PMID 21737131