iffconj.

Etymology: Arbitrary extension of if conj.

A written form of abbreviation of the phrase ‘if and only if’, always read as ‘if and only if’, used in Mathematics and Logic to introduce a condition that is necessary as well as sufficient, or a statement that is implied by and implies the preceding one.

ΘΚΠ

the mind > attention and judgement > testing > attestation, witness, evidence > qualification > [noun] > instance of > necessary condition

iff1955

1955 J. L. Kelley Gen. Topol. vii. 232 F is equicontinuous at x iff there is a neighborhood of x whose image under every member of F is small.

1961 R. R. Stoll Sets, Logic, & Axiomatic Theories i. 5 Two sets are equal iff (if and only if) they have the same members.

1964 T. O. Moore Elem. Gen. Topol. i. 2 We use ‘iff’ as an abbreviation for ‘if and only if’.

1965 B. Mates Elem. Logic viii. 137 ϕ ∈ Δ iff ϕ is derivable from Δ.

1971 G. Hunter Metalogic 16 Hereafter we abbreviate ‘if and only if’ to ‘iff’.

1972 Royal Inst. Philos. Lect. V. 34 An integer n is prime iff the only integers which divide it without remainder are itself and one.

This entry has not yet been fully updated (first published 1976; most recently modified version published online June 2018).

I.F.F. n. Identification, Friend or Foe.

1945 Electronic Engin. 17 686 An I.F.F. unit can be briefly described as being a transmitter-receiver device installed in friendly aircraft whose purpose is to reply to the interrogation of the friendly Radar station.

1961 Listener 30 Nov. 909/1 The I.F.F. radar identification sets in our bombers.

单词	iff
释义	iffconj. Etymology: Arbitrary extension of if conj. A written form of abbreviation of the phrase ‘if and only if’, always read as ‘if and only if’, used in Mathematics and Logic to introduce a condition that is necessary as well as sufficient, or a statement that is implied by and implies the preceding one. ΘΚΠ the mind > attention and judgement > testing > attestation, witness, evidence > qualification > [noun] > instance of > necessary condition iff1955 1955 J. L. Kelley Gen. Topol. vii. 232 F is equicontinuous at x iff there is a neighborhood of x whose image under every member of F is small. 1961 R. R. Stoll Sets, Logic, & Axiomatic Theories i. 5 Two sets are equal iff (if and only if) they have the same members. 1964 T. O. Moore Elem. Gen. Topol. i. 2 We use ‘iff’ as an abbreviation for ‘if and only if’. 1965 B. Mates Elem. Logic viii. 137 ϕ ∈ Δ iff ϕ is derivable from Δ. 1971 G. Hunter Metalogic 16 Hereafter we abbreviate ‘if and only if’ to ‘iff’. 1972 Royal Inst. Philos. Lect. V. 34 An integer n is prime iff the only integers which divide it without remainder are itself and one. This entry has not yet been fully updated (first published 1976; most recently modified version published online June 2018). > as lemmas I.F.F. I.F.F. n. Identification, Friend or Foe. Π 1945 Electronic Engin. 17 686 An I.F.F. unit can be briefly described as being a transmitter-receiver device installed in friendly aircraft whose purpose is to reply to the interrogation of the friendly Radar station. 1961 Listener 30 Nov. 909/1 The I.F.F. radar identification sets in our bombers. extracted from In.¹ < conj.1955 as lemmas
随便看	endentus ender enderest endergonic endermatic endermic endermic method endermical endermically endermost enderon enderonic enderons enders endew endfast endfire array endfire radiation endfull endfully endgame endgames endgate endgatherer endgrain

iffconj.

> as lemmas